linux/arch/x86/kvm
Sean Christopherson b68f3cc7d9 KVM: x86: Always use 32-bit SMRAM save state for 32-bit kernels
Invoking the 64-bit variation on a 32-bit kenrel will crash the guest,
trigger a WARN, and/or lead to a buffer overrun in the host, e.g.
rsm_load_state_64() writes r8-r15 unconditionally, but enum kvm_reg and
thus x86_emulate_ctxt._regs only define r8-r15 for CONFIG_X86_64.

KVM allows userspace to report long mode support via CPUID, even though
the guest is all but guaranteed to crash if it actually tries to enable
long mode.  But, a pure 32-bit guest that is ignorant of long mode will
happily plod along.

SMM complicates things as 64-bit CPUs use a different SMRAM save state
area.  KVM handles this correctly for 64-bit kernels, e.g. uses the
legacy save state map if userspace has hid long mode from the guest,
but doesn't fare well when userspace reports long mode support on a
32-bit host kernel (32-bit KVM doesn't support 64-bit guests).

Since the alternative is to crash the guest, e.g. by not loading state
or explicitly requesting shutdown, unconditionally use the legacy SMRAM
save state map for 32-bit KVM.  If a guest has managed to get far enough
to handle SMIs when running under a weird/buggy userspace hypervisor,
then don't deliberately crash the guest since there are no downsides
(from KVM's perspective) to allow it to continue running.

Fixes: 660a5d517a ("KVM: x86: save/load state on SMM switch")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-04-16 15:37:38 +02:00
..
vmx KVM: x86: clear SMM flags before loading state while leaving SMM 2019-04-16 15:37:36 +02:00
cpuid.c ARM: some cleanups, direct physical timer assignment, cache sanitization 2019-03-15 15:00:28 -07:00
cpuid.h KVM/x86: Update the reverse_cpuid list to include CPUID_7_EDX 2018-02-03 23:06:51 +01:00
debugfs.c kvm: x86: export TSC information to user-space 2016-09-16 16:57:48 +02:00
emulate.c KVM: x86: Always use 32-bit SMRAM save state for 32-bit kernels 2019-04-16 15:37:38 +02:00
hyperv.c x86/kvm/hyper-v: avoid spurious pending stimer on vCPU init 2019-03-28 17:29:03 +01:00
hyperv.h x86/kvm/hyper-v: Introduce KVM_GET_SUPPORTED_HV_CPUID 2018-12-14 17:59:54 +01:00
i8254.c kvm: x86: Add memcg accounting to KVM allocations 2019-02-20 22:48:30 +01:00
i8254.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
i8259.c kvm: x86: Add memcg accounting to KVM allocations 2019-02-20 22:48:30 +01:00
ioapic.c kvm: x86: Add memcg accounting to KVM allocations 2019-02-20 22:48:30 +01:00
ioapic.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
irq_comm.c KVM: x86: don't hold kvm->lock in KVM_SET_GSI_ROUTING 2017-05-02 14:45:45 +02:00
irq.c KVM: x86: Rename interrupt.pending to interrupt.injected 2018-03-28 22:47:06 +02:00
irq.h KVM: x86: don't hold kvm->lock in KVM_SET_GSI_ROUTING 2017-05-02 14:45:45 +02:00
Kconfig treewide: surround Kconfig file paths with double quotes 2018-12-22 00:25:54 +09:00
kvm_cache_regs.h KVM: x86: Add requisite includes to kvm_cache_regs.h 2018-12-14 12:34:22 +01:00
lapic.c kvm: x86: Add memcg accounting to KVM allocations 2019-02-20 22:48:30 +01:00
lapic.h KVM: hyperv: define VP assist page helpers 2018-10-17 00:30:13 +02:00
Makefile KVM: x86: fix TRACE_INCLUDE_PATH and remove -I. header search paths 2019-01-25 19:12:37 +01:00
mmu_audit.c x86/kvm/mmu: make vcpu->mmu a pointer to the current MMU 2018-10-17 00:30:02 +02:00
mmu.c kvm: mmu: Fix overflow on kvm mmu page limit calculation 2019-04-16 15:37:30 +02:00
mmu.h kvm: mmu: Fix overflow on kvm mmu page limit calculation 2019-04-16 15:37:30 +02:00
mmutrace.h KVM: x86: fix handling of role.cr4_pae and rename it to 'gpte_size' 2019-03-28 17:27:03 +01:00
mtrr.c KVM: x86: generalize guest_cpuid_has_ helpers 2017-08-07 16:11:50 +02:00
page_track.c kvm: x86: Add memcg accounting to KVM allocations 2019-02-20 22:48:30 +01:00
paging_tmpl.h KVM: Replace old tlb flush function with new one to flush a specified range. 2018-12-21 11:28:41 +01:00
pmu_amd.c KVM: x86: Add support for AMD Core Perf Extension in guest 2018-03-16 22:01:28 +01:00
pmu.c KVM: x86: Raise #GP when guest vCPU do not support PMU 2019-04-16 15:37:34 +02:00
pmu.h KVM: x86: Add support for VMware backdoor Pseudo-PMCs 2018-03-16 22:02:01 +01:00
svm.c KVM: x86: clear SMM flags before loading state while leaving SMM 2019-04-16 15:37:36 +02:00
trace.h KVM: x86: fix TRACE_INCLUDE_PATH and remove -I. header search paths 2019-01-25 19:12:37 +01:00
tss.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
x86.c KVM: x86: Always use 32-bit SMRAM save state for 32-bit kernels 2019-04-16 15:37:38 +02:00
x86.h x86/kvm: move kvm_load/put_guest_xcr0 into atomic context 2019-04-16 15:37:33 +02:00