linux/virt/kvm/arm
Mark Rutland da5a3ce66b KVM: arm64: Fix caching of host MDCR_EL2 value
At boot time, KVM stashes the host MDCR_EL2 value, but only does this
when the kernel is not running in hyp mode (i.e. is non-VHE). In these
cases, the stashed value of MDCR_EL2.HPMN happens to be zero, which can
lead to CONSTRAINED UNPREDICTABLE behaviour.

Since we use this value to derive the MDCR_EL2 value when switching
to/from a guest, after a guest have been run, the performance counters
do not behave as expected. This has been observed to result in accesses
via PMXEVTYPER_EL0 and PMXEVCNTR_EL0 not affecting the relevant
counters, resulting in events not being counted. In these cases, only
the fixed-purpose cycle counter appears to work as expected.

Fix this by always stashing the host MDCR_EL2 value, regardless of VHE.

Cc: Christopher Dall <christoffer.dall@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: stable@vger.kernel.org
Fixes: 1e947bad0b ("arm64: KVM: Skip HYP setup when already running in HYP")
Tested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-10-17 18:32:46 +01:00
..
hyp kvm/arm fixes for 4.16, take 2 2018-03-19 17:43:01 +00:00
vgic vgic: Add support for 52bit guest physical address 2018-10-01 13:50:32 +01:00
aarch32.c kvm/arm: use PSR_AA32 definitions 2018-07-05 17:24:15 +01:00
arch_timer.c KVM: arm/arm64: Fix lost IRQs from emulated physcial timer when blocked 2018-07-31 07:53:20 +01:00
arm.c KVM: arm64: Fix caching of host MDCR_EL2 value 2018-10-17 18:32:46 +01:00
mmio.c KVM: Fix stack-out-of-bounds read in write_mmio 2017-12-18 12:57:01 +01:00
mmu.c KVM: arm/arm64: Ensure only THP is candidate for adjustment 2018-10-03 11:49:34 +01:00
perf.c KVM: arm/arm64: Move shared files to virt/kvm/arm 2017-05-04 13:57:26 +02:00
pmu.c KVM: arm64: Rewrite system register accessors to read/write functions 2018-03-19 10:53:16 +00:00
psci.c sched/swait: Rename to exclusive 2018-06-20 11:35:56 +02:00
trace.h KVM: Remove obsolete kvm_unmap_hva notifier backend 2018-09-07 15:06:02 +02:00