Almost all logic is moved to C, by introducing a new in_guest mode for
the P9 path that branches very early in the KVM interrupt handler to P9
exit code.
The main P9 entry and exit assembly is now only about 160 lines of low
level stack setup and register save/restore, plus a bad-interrupt
handler.
There are two motivations for this, the first is just make the code more
maintainable being in C. The second is to reduce the amount of code
running in a special KVM mode, "realmode". In quotes because with radix
it is no longer necessarily real-mode in the MMU, but it still has to be
treated specially because it may be in real-mode, and has various
important registers like PID, DEC, TB, etc set to guest. This is hostile
to the rest of Linux and can't use arbitrary kernel functionality or be
instrumented well.
This initial patch is a reasonably faithful conversion of the asm code,
but it does lack any loop to return quickly back into the guest without
switching out of realmode in the case of unimportant or easily handled
interrupts. As explained in previous changes, handling HV interrupts
very quickly in this low level realmode is not so important for P9
performance, and are important to avoid for security, observability,
debugability reasons.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210528090752.3542186-15-npiggin@gmail.com
In the interest of minimising the amount of code that is run in
"real-mode", don't handle hcalls in real mode in the P9 path. This
requires some new handlers for H_CEDE and xics-on-xive to be added
before xive is pulled or cede logic is checked.
This introduces a change in radix guest behaviour where radix guests
that execute 'sc 1' in userspace now get a privilege fault whereas
previously the 'sc 1' would be reflected as a syscall interrupt to the
guest kernel. That reflection is only required for hash guests that run
PR KVM.
Background:
In POWER8 and earlier processors, it is very expensive to exit from the
HV real mode context of a guest hypervisor interrupt, and switch to host
virtual mode. On those processors, guest->HV interrupts reach the
hypervisor with the MMU off because the MMU is loaded with guest context
(LPCR, SDR1, SLB), and the other threads in the sub-core need to be
pulled out of the guest too. Then the primary must save off guest state,
invalidate SLB and ERAT, and load up host state before the MMU can be
enabled to run in host virtual mode (~= regular Linux mode).
Hash guests also require a lot of hcalls to run due to the nature of the
MMU architecture and paravirtualisation design. The XICS interrupt
controller requires hcalls to run.
So KVM traditionally tries hard to avoid the full exit, by handling
hcalls and other interrupts in real mode as much as possible.
By contrast, POWER9 has independent MMU context per-thread, and in radix
mode the hypervisor is in host virtual memory mode when the HV interrupt
is taken. Radix guests do not require significant hcalls to manage their
translations, and xive guests don't need hcalls to handle interrupts. So
it's much less important for performance to handle hcalls in real mode on
POWER9.
One caveat is that the TCE hcalls are performance critical, real-mode
variants introduced for POWER8 in order to achieve 10GbE performance.
Real mode TCE hcalls were found to be less important on POWER9, which
was able to drive 40GBe networking without them (using the virt mode
hcalls) but performance is still important. These hcalls will benefit
from subsequent guest entry/exit optimisation including possibly a
faster "partial exit" that does not entirely switch to host context to
handle the hcall.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210528090752.3542186-14-npiggin@gmail.com
Switching the MMU from radix<->radix mode is tricky particularly as the
MMU can remain enabled and requires a certain sequence of SPR updates.
Move these together into their own functions.
This also includes the radix TLB check / flush because it's tied in to
MMU switching due to tlbiel getting LPID from LPIDR.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210528090752.3542186-13-npiggin@gmail.com
LPCR[HDICE]=0 suppresses hypervisor decrementer exceptions on some
processors, so it must be enabled before HDEC is set.
Rather than set it in the host LPCR then setting HDEC, move the HDEC
update to after the guest MMU context (including LPCR) is loaded.
There shouldn't be much concern with delaying HDEC by some 10s or 100s
of nanoseconds by setting it a bit later.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210528090752.3542186-10-npiggin@gmail.com
Pull powerpc fixes from Michael Ellerman:
"Fix our KVM reverse map real-mode handling since we enabled huge
vmalloc (in some configurations).
Revert a recent change to our IOMMU code which broke some devices.
Fix KVM handling of FSCR on P7/P8, which could have possibly let a
guest crash it's Qemu.
Fix kprobes validation of prefixed instructions across page boundary.
Thanks to Alexey Kardashevskiy, Christophe Leroy, Fabiano Rosas,
Frederic Barrat, Naveen N. Rao, and Nicholas Piggin"
* tag 'powerpc-5.13-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
Revert "powerpc/kernel/iommu: Align size for IOMMU_PAGE_SIZE() to save TCEs"
KVM: PPC: Book3S HV: Save host FSCR in the P7/8 path
powerpc: Fix reverse map real-mode address lookup with huge vmalloc
powerpc/kprobes: Fix validation of prefixed instructions across page boundary
Similar to commit 25edcc50d7 ("KVM: PPC: Book3S HV: Save and restore
FSCR in the P9 path"), ensure the P7/8 path saves and restores the host
FSCR. The logic explained in that patch actually applies there to the
old path well: a context switch can be made before kvmppc_vcpu_run_hv
restores the host FSCR and returns.
Now both the p9 and the p7/8 paths now save and restore their FSCR, it
no longer needs to be restored at the end of kvmppc_vcpu_run_hv
Fixes: b005255e12 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs")
Cc: stable@vger.kernel.org # v3.14+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210526125851.3436735-1-npiggin@gmail.com
Similar to commit 25edcc50d7 ("KVM: PPC: Book3S HV: Save and restore
FSCR in the P9 path"), ensure the P7/8 path saves and restores the host
FSCR. The logic explained in that patch actually applies there to the
old path well: a context switch can be made before kvmppc_vcpu_run_hv
restores the host FSCR and returns.
Now both the p9 and the p7/8 paths now save and restore their FSCR, it
no longer needs to be restored at the end of kvmppc_vcpu_run_hv
Fixes: b005255e12 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs")
Cc: stable@vger.kernel.org # v3.14+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210526125851.3436735-1-npiggin@gmail.com
Pull kvm updates from Paolo Bonzini:
"This is a large update by KVM standards, including AMD PSP (Platform
Security Processor, aka "AMD Secure Technology") and ARM CoreSight
(debug and trace) changes.
ARM:
- CoreSight: Add support for ETE and TRBE
- Stage-2 isolation for the host kernel when running in protected
mode
- Guest SVE support when running in nVHE mode
- Force W^X hypervisor mappings in nVHE mode
- ITS save/restore for guests using direct injection with GICv4.1
- nVHE panics now produce readable backtraces
- Guest support for PTP using the ptp_kvm driver
- Performance improvements in the S2 fault handler
x86:
- AMD PSP driver changes
- Optimizations and cleanup of nested SVM code
- AMD: Support for virtual SPEC_CTRL
- Optimizations of the new MMU code: fast invalidation, zap under
read lock, enable/disably dirty page logging under read lock
- /dev/kvm API for AMD SEV live migration (guest API coming soon)
- support SEV virtual machines sharing the same encryption context
- support SGX in virtual machines
- add a few more statistics
- improved directed yield heuristics
- Lots and lots of cleanups
Generic:
- Rework of MMU notifier interface, simplifying and optimizing the
architecture-specific code
- a handful of "Get rid of oprofile leftovers" patches
- Some selftests improvements"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (379 commits)
KVM: selftests: Speed up set_memory_region_test
selftests: kvm: Fix the check of return value
KVM: x86: Take advantage of kvm_arch_dy_has_pending_interrupt()
KVM: SVM: Skip SEV cache flush if no ASIDs have been used
KVM: SVM: Remove an unnecessary prototype declaration of sev_flush_asids()
KVM: SVM: Drop redundant svm_sev_enabled() helper
KVM: SVM: Move SEV VMCB tracking allocation to sev.c
KVM: SVM: Explicitly check max SEV ASID during sev_hardware_setup()
KVM: SVM: Unconditionally invoke sev_hardware_teardown()
KVM: SVM: Enable SEV/SEV-ES functionality by default (when supported)
KVM: SVM: Condition sev_enabled and sev_es_enabled on CONFIG_KVM_AMD_SEV=y
KVM: SVM: Append "_enabled" to module-scoped SEV/SEV-ES control variables
KVM: SEV: Mask CPUID[0x8000001F].eax according to supported features
KVM: SVM: Move SEV module params/variables to sev.c
KVM: SVM: Disable SEV/SEV-ES if NPT is disabled
KVM: SVM: Free sev_asid_bitmap during init if SEV setup fails
KVM: SVM: Zero out the VMCB array used to track SEV ASID association
x86/sev: Drop redundant and potentially misleading 'sev_enabled'
KVM: x86: Move reverse CPUID helpers to separate header file
KVM: x86: Rename GPR accessors to make mode-aware variants the defaults
...
Move PPC to the gfn-base MMU notifier APIs, and update all 15 bajillion
PPC-internal hooks to work with gfns instead of hvas.
No meaningful functional change intended, though the exact order of
operations is slightly different since the memslot lookups occur before
calling into arch code.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210402005658.3024832-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Guest LPCR depends on hardware type, and future changes will add
restrictions based on errata and guest MMU mode. Move this logic
to a common function and use it for the cases where the guest
wants to update its LPCR (or the LPCR of a nested guest).
This also adds a warning in other places that set or update LPCR
if we try to set something that would have been disallowed by
the filter, as a sanity check.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210412014845.1517916-4-npiggin@gmail.com
The host CTRL (runlatch) value is not restored after guest exit. The
host CTRL should always be 1 except in CPU idle code, so this can result
in the host running with runlatch clear, and potentially switching to
a different vCPU which then runs with runlatch clear as well.
This has little effect on P9 machines, CTRL is only responsible for some
PMU counter logic in the host and so other than corner cases of software
relying on that, or explicitly reading the runlatch value (Linux does
not appear to be affected but it's possible non-Linux guests could be),
there should be no execution correctness problem, though it could be
used as a covert channel between guests.
There may be microcontrollers, firmware or monitoring tools that sample
the runlatch value out-of-band, however since the register is writable
by guests, these values would (should) not be relied upon for correct
operation of the host, so suboptimal performance or incorrect reporting
should be the worst problem.
Fixes: 95a6432ce9 ("KVM: PPC: Book3S HV: Streamlined guest entry/exit path on P9 for radix guests")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210412014845.1517916-2-npiggin@gmail.com
Pull powerpc updates from Michael Ellerman:
- A large series adding wrappers for our interrupt handlers, so that
irq/nmi/user tracking can be isolated in the wrappers rather than
spread in each handler.
- Conversion of the 32-bit syscall handling into C.
- A series from Nick to streamline our TLB flushing when using the
Radix MMU.
- Switch to using queued spinlocks by default for 64-bit server CPUs.
- A rework of our PCI probing so that it happens later in boot, when
more generic infrastructure is available.
- Two small fixes to allow 32-bit little-endian processes to run on
64-bit kernels.
- Other smaller features, fixes & cleanups.
Thanks to: Alexey Kardashevskiy, Ananth N Mavinakayanahalli, Aneesh
Kumar K.V, Athira Rajeev, Bhaskar Chowdhury, Cédric Le Goater, Chengyang
Fan, Christophe Leroy, Christopher M. Riedl, Fabiano Rosas, Florian
Fainelli, Frederic Barrat, Ganesh Goudar, Hari Bathini, Jiapeng Chong,
Joseph J Allen, Kajol Jain, Markus Elfring, Michal Suchanek, Nathan
Lynch, Naveen N. Rao, Nicholas Piggin, Oliver O'Halloran, Pingfan Liu,
Po-Hsu Lin, Qian Cai, Ram Pai, Randy Dunlap, Sandipan Das, Stephen
Rothwell, Tyrel Datwyler, Will Springer, Yury Norov, and Zheng Yongjun.
* tag 'powerpc-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (188 commits)
powerpc/perf: Adds support for programming of Thresholding in P10
powerpc/pci: Remove unimplemented prototypes
powerpc/uaccess: Merge raw_copy_to_user_allowed() into raw_copy_to_user()
powerpc/uaccess: Merge __put_user_size_allowed() into __put_user_size()
powerpc/uaccess: get rid of small constant size cases in raw_copy_{to,from}_user()
powerpc/64: Fix stack trace not displaying final frame
powerpc/time: Remove get_tbl()
powerpc/time: Avoid using get_tbl()
spi: mpc52xx: Avoid using get_tbl()
powerpc/syscall: Avoid storing 'current' in another pointer
powerpc/32: Handle bookE debugging in C in syscall entry/exit
powerpc/syscall: Do not check unsupported scv vector on PPC32
powerpc/32: Remove the counter in global_dbcr0
powerpc/32: Remove verification of MSR_PR on syscall in the ASM entry
powerpc/syscall: implement system call entry/exit logic in C for PPC32
powerpc/32: Always save non volatile GPRs at syscall entry
powerpc/syscall: Change condition to check MSR_RI
powerpc/syscall: Save r3 in regs->orig_r3
powerpc/syscall: Use is_compat_task()
powerpc/syscall: Make interrupt.c buildable on PPC32
...
These machines don't support running both MMU types at the same time,
so remove the KVM_CAP_PPC_MMU_HASH_V3 capability when the host is
using Radix MMU.
[paulus@ozlabs.org - added defensive check on
kvmppc_hv_ops->hash_v3_possible]
Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
The Facility Status and Control Register is a privileged SPR that
defines the availability of some features in problem state. Since it
can be written by the guest, we must restore it to the previous host
value after guest exit.
This restoration is currently done by taking the value from
current->thread.fscr, which in the P9 path is not enough anymore
because the guest could context switch the QEMU thread, causing the
guest-current value to be saved into the thread struct.
The above situation manifested when running a QEMU linked against a
libc with System Call Vectored support, which causes scv
instructions to be run by QEMU early during the guest boot (during
SLOF), at which point the FSCR is 0 due to guest entry. After a few
scv calls (1 to a couple hundred), the context switching happens and
the QEMU thread runs with the guest value, resulting in a Facility
Unavailable interrupt.
This patch saves and restores the host value of FSCR in the inner
guest entry loop in a way independent of current->thread.fscr. The old
way of doing it is still kept in place because it works for the old
entry path.
Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This reverts much of commit c01015091a ("KVM: PPC: Book3S HV: Run HPT
guests on POWER9 radix hosts"), which was required to run HPT guests on
RPT hosts on early POWER9 CPUs without support for "mixed mode", which
meant the host could not run with MMU on while guests were running.
This code has some corner case bugs, e.g., when the guest hits a machine
check or HMI the primary locks up waiting for secondaries to switch LPCR
to host, which they never do. This could all be fixed in software, but
most CPUs in production have mixed mode support, and those that don't
are believed to be all in installations that don't use this capability.
So simplify things and remove support.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Introduce KVM_CAP_PPC_DAWR1 which can be used by QEMU to query whether
KVM supports 2nd DAWR or not. The capability is by default disabled
even when the underlying CPU supports 2nd DAWR. QEMU needs to check
and enable it manually to use the feature.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
KVM code assumes single DAWR everywhere. Add code to support 2nd DAWR.
DAWR is a hypervisor resource and thus H_SET_MODE hcall is used to set/
unset it. Introduce new case H_SET_MODE_RESOURCE_SET_DAWR1 for 2nd DAWR.
Also, KVM will support 2nd DAWR only if CPU_FTR_DAWR1 is set.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Power10 is introducing a second DAWR (Data Address Watchpoint
Register). Use real register names (with suffix 0) from ISA for
current macros and variables used by kvm. One exception is
KVM_REG_PPC_DAWR. Keep it as it is because it's uapi so changing it
will break userspace.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Interrupts that occur in kernel mode expect that context tracking
is set to kernel. Enabling local irqs before context tracking
switches from guest to host means interrupts can come in and trigger
warnings about wrong context, and possibly worse.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210130130852.2952424-3-npiggin@gmail.com
According to ISAv3.1 and ISAv3.0b, the msgsndp is described to split
RB in:
msgtype <- (RB) 32:36
payload <- (RB) 37:63
t <- (RB) 57:63
The current way of getting 'msgtype', and 't' is missing their MSB:
msgtype: ((arg >> 27) & 0xf) : Gets (RB) 33:36, missing bit 32
t: (arg &= 0x3f) : Gets (RB) 58:63, missing bit 57
Fixes this by applying the correct mask.
Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201208215707.31149-1-leobras.c@gmail.com
Pull KVM updates from Paolo Bonzini:
"For x86, there is a new alternative and (in the future) more scalable
implementation of extended page tables that does not need a reverse
map from guest physical addresses to host physical addresses.
For now it is disabled by default because it is still lacking a few of
the existing MMU's bells and whistles. However it is a very solid
piece of work and it is already available for people to hammer on it.
Other updates:
ARM:
- New page table code for both hypervisor and guest stage-2
- Introduction of a new EL2-private host context
- Allow EL2 to have its own private per-CPU variables
- Support of PMU event filtering
- Complete rework of the Spectre mitigation
PPC:
- Fix for running nested guests with in-kernel IRQ chip
- Fix race condition causing occasional host hard lockup
- Minor cleanups and bugfixes
x86:
- allow trapping unknown MSRs to userspace
- allow userspace to force #GP on specific MSRs
- INVPCID support on AMD
- nested AMD cleanup, on demand allocation of nested SVM state
- hide PV MSRs and hypercalls for features not enabled in CPUID
- new test for MSR_IA32_TSC writes from host and guest
- cleanups: MMU, CPUID, shared MSRs
- LAPIC latency optimizations ad bugfixes"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (232 commits)
kvm: x86/mmu: NX largepage recovery for TDP MMU
kvm: x86/mmu: Don't clear write flooding count for direct roots
kvm: x86/mmu: Support MMIO in the TDP MMU
kvm: x86/mmu: Support write protection for nesting in tdp MMU
kvm: x86/mmu: Support disabling dirty logging for the tdp MMU
kvm: x86/mmu: Support dirty logging for the TDP MMU
kvm: x86/mmu: Support changed pte notifier in tdp MMU
kvm: x86/mmu: Add access tracking for tdp_mmu
kvm: x86/mmu: Support invalidate range MMU notifier for TDP MMU
kvm: x86/mmu: Allocate struct kvm_mmu_pages for all pages in TDP MMU
kvm: x86/mmu: Add TDP MMU PF handler
kvm: x86/mmu: Remove disallowed_hugepage_adjust shadow_walk_iterator arg
kvm: x86/mmu: Support zapping SPTEs in the TDP MMU
KVM: Cache as_id in kvm_memory_slot
kvm: x86/mmu: Add functions to handle changed TDP SPTEs
kvm: x86/mmu: Allocate and free TDP MMU roots
kvm: x86/mmu: Init / Uninit the TDP MMU
kvm: x86/mmu: Introduce tdp_iter
KVM: mmu: extract spte.h and spte.c
KVM: mmu: Separate updating a PTE from kvm_set_pte_rmapp
...
Build the kernel with `C=2`:
arch/powerpc/kvm/book3s_hv_nested.c:572:25: warning: symbol
'kvmhv_alloc_nested' was not declared. Should it be static?
arch/powerpc/kvm/book3s_64_mmu_radix.c:350:6: warning: symbol
'kvmppc_radix_set_pte_at' was not declared. Should it be static?
arch/powerpc/kvm/book3s_hv.c:3568:5: warning: symbol
'kvmhv_p9_guest_entry' was not declared. Should it be static?
arch/powerpc/kvm/book3s_hv_rm_xics.c:767:15: warning: symbol 'eoi_rc'
was not declared. Should it be static?
arch/powerpc/kvm/book3s_64_vio_hv.c:240:13: warning: symbol
'iommu_tce_kill_rm' was not declared. Should it be static?
arch/powerpc/kvm/book3s_64_vio.c:492:6: warning: symbol
'kvmppc_tce_iommu_do_map' was not declared. Should it be static?
arch/powerpc/kvm/book3s_pr.c:572:6: warning: symbol 'kvmppc_set_pvr_pr'
was not declared. Should it be static?
Those symbols are used only in the files that define them so make them
static to fix the warnings.
Signed-off-by: Wang Wensheng <wangwensheng4@huawei.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
POWER8 and POWER9 machines have a hardware deviation where generation
of a hypervisor decrementer exception is suppressed if the HDICE bit
in the LPCR register is 0 at the time when the HDEC register
decrements from 0 to -1. When entering a guest, KVM first writes the
HDEC register with the time until it wants the CPU to exit the guest,
and then writes the LPCR with the guest value, which includes
HDICE = 1. If HDEC decrements from 0 to -1 during the interval
between those two events, it is possible that we can enter the guest
with HDEC already negative but no HDEC exception pending, meaning that
no HDEC interrupt will occur while the CPU is in the guest, or at
least not until HDEC wraps around. Thus it is possible for the CPU to
keep executing in the guest for a long time; up to about 4 seconds on
POWER8, or about 4.46 years on POWER9 (except that the host kernel
hard lockup detector will fire first).
To fix this, we set the LPCR[HDICE] bit before writing HDEC on guest
entry.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
The current nested KVM code does not support HPT guests. This is
informed/enforced in some ways:
- Hosts < P9 will not be able to enable the nested HV feature;
- The nested hypervisor MMU capabilities will not contain
KVM_CAP_PPC_MMU_HASH_V3;
- QEMU reflects the MMU capabilities in the
'ibm,arch-vec-5-platform-support' device-tree property;
- The nested guest, at 'prom_parse_mmu_model' ignores the
'disable_radix' kernel command line option if HPT is not supported;
- The KVM_PPC_CONFIGURE_V3_MMU ioctl will fail if trying to use HPT.
There is, however, still a way to start a HPT guest by using
max-compat-cpu=power8 at the QEMU machine options. This leads to the
guest being set to use hash after QEMU calls the KVM_PPC_ALLOCATE_HTAB
ioctl.
With the guest set to hash, the nested hypervisor goes through the
entry path that has no knowledge of nesting (kvmppc_run_vcpu) and
crashes when it tries to execute an hypervisor-privileged (mtspr
HDEC) instruction at __kvmppc_vcore_entry:
root@L1:~ $ qemu-system-ppc64 -machine pseries,max-cpu-compat=power8 ...
<snip>
[ 538.543303] CPU: 83 PID: 25185 Comm: CPU 0/KVM Not tainted 5.9.0-rc4 #1
[ 538.543355] NIP: c00800000753f388 LR: c00800000753f368 CTR: c0000000001e5ec0
[ 538.543417] REGS: c0000013e91e33b0 TRAP: 0700 Not tainted (5.9.0-rc4)
[ 538.543470] MSR: 8000000002843033 <SF,VEC,VSX,FP,ME,IR,DR,RI,LE> CR: 22422882 XER: 20040000
[ 538.543546] CFAR: c00800000753f4b0 IRQMASK: 3
GPR00: c0080000075397a0 c0000013e91e3640 c00800000755e600 0000000080000000
GPR04: 0000000000000000 c0000013eab19800 c000001394de0000 00000043a054db72
GPR08: 00000000003b1652 0000000000000000 0000000000000000 c0080000075502e0
GPR12: c0000000001e5ec0 c0000007ffa74200 c0000013eab19800 0000000000000008
GPR16: 0000000000000000 c00000139676c6c0 c000000001d23948 c0000013e91e38b8
GPR20: 0000000000000053 0000000000000000 0000000000000001 0000000000000000
GPR24: 0000000000000001 0000000000000001 0000000000000000 0000000000000001
GPR28: 0000000000000001 0000000000000053 c0000013eab19800 0000000000000001
[ 538.544067] NIP [c00800000753f388] __kvmppc_vcore_entry+0x90/0x104 [kvm_hv]
[ 538.544121] LR [c00800000753f368] __kvmppc_vcore_entry+0x70/0x104 [kvm_hv]
[ 538.544173] Call Trace:
[ 538.544196] [c0000013e91e3640] [c0000013e91e3680] 0xc0000013e91e3680 (unreliable)
[ 538.544260] [c0000013e91e3820] [c0080000075397a0] kvmppc_run_core+0xbc8/0x19d0 [kvm_hv]
[ 538.544325] [c0000013e91e39e0] [c00800000753d99c] kvmppc_vcpu_run_hv+0x404/0xc00 [kvm_hv]
[ 538.544394] [c0000013e91e3ad0] [c0080000072da4fc] kvmppc_vcpu_run+0x34/0x48 [kvm]
[ 538.544472] [c0000013e91e3af0] [c0080000072d61b8] kvm_arch_vcpu_ioctl_run+0x310/0x420 [kvm]
[ 538.544539] [c0000013e91e3b80] [c0080000072c7450] kvm_vcpu_ioctl+0x298/0x778 [kvm]
[ 538.544605] [c0000013e91e3ce0] [c0000000004b8c2c] sys_ioctl+0x1dc/0xc90
[ 538.544662] [c0000013e91e3dc0] [c00000000002f9a4] system_call_exception+0xe4/0x1c0
[ 538.544726] [c0000013e91e3e20] [c00000000000d140] system_call_common+0xf0/0x27c
[ 538.544787] Instruction dump:
[ 538.544821] f86d1098 60000000 60000000 48000099 e8ad0fe8 e8c500a0 e9264140 75290002
[ 538.544886] 7d1602a6 7cec42a6 40820008 7d0807b4 <7d164ba6> 7d083a14 f90d10a0 480104fd
[ 538.544953] ---[ end trace 74423e2b948c2e0c ]---
This patch makes the KVM_PPC_ALLOCATE_HTAB ioctl fail when running in
the nested hypervisor, causing QEMU to abort.
Reported-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
The ISA v3.1 the copy-paste facility has a new memory move functionality
which allows the copy buffer to be pasted to domestic memory (RAM) as
opposed to foreign memory (accelerator).
This means the POWER9 trick of avoiding the cp_abort on context switch if
the process had not mapped foreign memory does not work on POWER10. Do the
cp_abort unconditionally there.
KVM must also cp_abort on guest exit to prevent copy buffer state leaking
between contexts.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200825075535.224536-1-npiggin@gmail.com
PPC KVM update for 5.9
- Improvements and bug-fixes for secure VM support, giving reduced startup
time and memory hotplug support.
- Locking fixes in nested KVM code
- Increase number of guests supported by HV KVM to 4094
- Preliminary POWER10 support
Pull powerpc updates from Michael Ellerman:
- Add support for (optionally) using queued spinlocks & rwlocks.
- Support for a new faster system call ABI using the scv instruction on
Power9 or later.
- Drop support for the PROT_SAO mmap/mprotect flag as it will be
unsupported on Power10 and future processors, leaving us with no way
to implement the functionality it requests. This risks breaking
userspace, though we believe it is unused in practice.
- A bug fix for, and then the removal of, our custom stack expansion
checking. We now allow stack expansion up to the rlimit, like other
architectures.
- Remove the remnants of our (previously disabled) topology update
code, which tried to react to NUMA layout changes on virtualised
systems, but was prone to crashes and other problems.
- Add PMU support for Power10 CPUs.
- A change to our signal trampoline so that we don't unbalance the link
stack (branch return predictor) in the signal delivery path.
- Lots of other cleanups, refactorings, smaller features and so on as
usual.
Thanks to: Abhishek Goel, Alastair D'Silva, Alexander A. Klimov, Alexey
Kardashevskiy, Alistair Popple, Andrew Donnellan, Aneesh Kumar K.V, Anju
T Sudhakar, Anton Blanchard, Arnd Bergmann, Athira Rajeev, Balamuruhan
S, Bharata B Rao, Bill Wendling, Bin Meng, Cédric Le Goater, Chris
Packham, Christophe Leroy, Christoph Hellwig, Daniel Axtens, Dan
Williams, David Lamparter, Desnes A. Nunes do Rosario, Erhard F., Finn
Thain, Frederic Barrat, Ganesh Goudar, Gautham R. Shenoy, Geoff Levand,
Greg Kurz, Gustavo A. R. Silva, Hari Bathini, Harish, Imre Kaloz, Joel
Stanley, Joe Perches, John Crispin, Jordan Niethe, Kajol Jain, Kamalesh
Babulal, Kees Cook, Laurent Dufour, Leonardo Bras, Li RongQing, Madhavan
Srinivasan, Mahesh Salgaonkar, Mark Cave-Ayland, Michal Suchanek, Milton
Miller, Mimi Zohar, Murilo Opsfelder Araujo, Nathan Chancellor, Nathan
Lynch, Naveen N. Rao, Nayna Jain, Nicholas Piggin, Oliver O'Halloran,
Palmer Dabbelt, Pedro Miraglia Franco de Carvalho, Philippe Bergheaud,
Pingfan Liu, Pratik Rajesh Sampat, Qian Cai, Qinglang Miao, Randy
Dunlap, Ravi Bangoria, Sachin Sant, Sam Bobroff, Sandipan Das, Santosh
Sivaraj, Satheesh Rajendran, Shirisha Ganta, Sourabh Jain, Srikar
Dronamraju, Stan Johnson, Stephen Rothwell, Thadeu Lima de Souza
Cascardo, Thiago Jung Bauermann, Tom Lane, Vaibhav Jain, Vladis Dronov,
Wei Yongjun, Wen Xiong, YueHaibing.
* tag 'powerpc-5.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (337 commits)
selftests/powerpc: Fix pkey syscall redefinitions
powerpc: Fix circular dependency between percpu.h and mmu.h
powerpc/powernv/sriov: Fix use of uninitialised variable
selftests/powerpc: Skip vmx/vsx/tar/etc tests on older CPUs
powerpc/40x: Fix assembler warning about r0
powerpc/papr_scm: Add support for fetching nvdimm 'fuel-gauge' metric
powerpc/papr_scm: Fetch nvdimm performance stats from PHYP
cpuidle: pseries: Fixup exit latency for CEDE(0)
cpuidle: pseries: Add function to parse extended CEDE records
cpuidle: pseries: Set the latency-hint before entering CEDE
selftests/powerpc: Fix online CPU selection
powerpc/perf: Consolidate perf_callchain_user_[64|32]()
powerpc/pseries/hotplug-cpu: Remove double free in error path
powerpc/pseries/mobility: Add pr_debug() for device tree changes
powerpc/pseries/mobility: Set pr_fmt()
powerpc/cacheinfo: Warn if cache object chain becomes unordered
powerpc/cacheinfo: Improve diagnostics about malformed cache lists
powerpc/cacheinfo: Use name@unit instead of full DT path in debug messages
powerpc/cacheinfo: Set pr_fmt()
powerpc: fix function annotations to avoid section mismatch warnings with gcc-10
...
When a memory slot is hot plugged to a SVM, PFNs associated with the
GFNs in that slot must be migrated to the secure-PFNs, aka device-PFNs.
Call kvmppc_uv_migrate_mem_slot() to accomplish this.
Disable page-merge for all pages in the memory slot.
Reviewed-by: Bharata B Rao <bharata@linux.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
[rearranged the code, and modified the commit log]
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Power ISA v3.1 has added new performance monitoring unit (PMU) special
purpose registers (SPRs). They are:
Monitor Mode Control Register 3 (MMCR3)
Sampled Instruction Event Register A (SIER2)
Sampled Instruction Event Register B (SIER3)
Add support to save/restore these new SPRs while entering/exiting
guest. Also include changes to support KVM_REG_PPC_MMCR3/SIER2/SIER3.
Add new SPRs to KVM API documentation.
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1594996707-3727-6-git-send-email-atrajeev@linux.vnet.ibm.com
Currently `kvm_vcpu_arch` stores all Monitor Mode Control registers
in a flat array in order: mmcr0, mmcr1, mmcra, mmcr2, mmcrs
Split this to give mmcra and mmcrs its own entries in vcpu and
use a flat array for mmcr0 to mmcr2. This patch implements this
cleanup to make code easier to read.
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
[mpe: Fix MMCRA/MMCR2 uapi breakage as noted by paulus]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1594996707-3727-3-git-send-email-atrajeev@linux.vnet.ibm.com
Adds support for emulating ISAv3.1 guests by adding the appropriate PCR
and FSCR bits.
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Pull more KVM updates from Paolo Bonzini:
"The guest side of the asynchronous page fault work has been delayed to
5.9 in order to sync with Thomas's interrupt entry rework, but here's
the rest of the KVM updates for this merge window.
MIPS:
- Loongson port
PPC:
- Fixes
ARM:
- Fixes
x86:
- KVM_SET_USER_MEMORY_REGION optimizations
- Fixes
- Selftest fixes"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (62 commits)
KVM: x86: do not pass poisoned hva to __kvm_set_memory_region
KVM: selftests: fix sync_with_host() in smm_test
KVM: async_pf: Inject 'page ready' event only if 'page not present' was previously injected
KVM: async_pf: Cleanup kvm_setup_async_pf()
kvm: i8254: remove redundant assignment to pointer s
KVM: x86: respect singlestep when emulating instruction
KVM: selftests: Don't probe KVM_CAP_HYPERV_ENLIGHTENED_VMCS when nested VMX is unsupported
KVM: selftests: do not substitute SVM/VMX check with KVM_CAP_NESTED_STATE check
KVM: nVMX: Consult only the "basic" exit reason when routing nested exit
KVM: arm64: Move hyp_symbol_addr() to kvm_asm.h
KVM: arm64: Synchronize sysreg state on injecting an AArch32 exception
KVM: arm64: Make vcpu_cp1x() work on Big Endian hosts
KVM: arm64: Remove host_cpu_context member from vcpu structure
KVM: arm64: Stop sparse from moaning at __hyp_this_cpu_ptr
KVM: arm64: Handle PtrAuth traps early
KVM: x86: Unexport x86_fpu_cache and make it static
KVM: selftests: Ignore KVM 5-level paging support for VM_MODE_PXXV48_4K
KVM: arm64: Save the host's PtrAuth keys in non-preemptible context
KVM: arm64: Stop save/restoring ACTLR_EL1
KVM: arm64: Add emulation for 32bit guests accessing ACTLR2
...
