| Message ID | 20181112082707.26785-1-marc.zyngier@arm.com |
|---|---|
| State | New |
| Headers | show |
| Series | [stable-4.9] KVM: arm64: Fix caching of host MDCR_EL2 value | expand |
On Mon, Nov 12, 2018 at 08:27:07AM +0000, Marc Zyngier wrote: > From: Mark Rutland <mark.rutland@arm.com> > > commit da5a3ce66b8bb51b0ea8a89f42aac153903f90fb upstream. > > 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: 1e947bad0b63b351 ("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> > --- > arch/arm/kvm/arm.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) Now queued up, thanks. greg k-h
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 20436972537f..a670c70f4def 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -1092,8 +1092,6 @@ static void cpu_init_hyp_mode(void *dummy) __cpu_init_hyp_mode(pgd_ptr, hyp_stack_ptr, vector_ptr); __cpu_init_stage2(); - - kvm_arm_init_debug(); } static void cpu_hyp_reinit(void) @@ -1108,6 +1106,8 @@ static void cpu_hyp_reinit(void) if (__hyp_get_vectors() == hyp_default_vectors) cpu_init_hyp_mode(NULL); } + + kvm_arm_init_debug(); } static void cpu_hyp_reset(void)