On 5/8/19 12:02 PM, Borislav Petkov wrote: > From: Borislav Petkov <[email protected]> > > After commit: > > 672ff6cff80c ("KVM: x86: Raise #GP when guest vCPU do not support PMU")
You should add this commit as a fixes tag. Since that commit went into 5.1 it would be worth this fix going into the 5.1 stable tree. Thanks, Tom > > my AMD guests started #GPing like this: > > general protection fault: 0000 [#1] PREEMPT SMP > CPU: 1 PID: 4355 Comm: bash Not tainted 5.1.0-rc6+ #3 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 > 04/01/2014 > RIP: 0010:x86_perf_event_update+0x3b/0xa0 > > with Code: pointing to RDPMC. It is RDPMC because the guest has the > hardware watchdog CONFIG_HARDLOCKUP_DETECTOR_PERF enabled which uses > perf. Instrumenting kvm_pmu_rdpmc() some, showed that it fails due to: > > if (!pmu->version) > return 1; > > which the above commit added. Since AMD's PMU leaves the version at 0, > that causes the #GP injection into the guest. > > Set pmu->version arbitrarily to 1 and move it above the non-applicable > struct kvm_pmu members. > > Signed-off-by: Borislav Petkov <[email protected]> > Cc: "H. Peter Anvin" <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Janakarajan Natarajan <[email protected]> > Cc: [email protected] > Cc: Liran Alon <[email protected]> > Cc: Mihai Carabas <[email protected]> > Cc: Paolo Bonzini <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: "Radim Krčmář" <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: Tom Lendacky <[email protected]> > Cc: [email protected] > --- > arch/x86/kvm/pmu_amd.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/pmu_amd.c b/arch/x86/kvm/pmu_amd.c > index 1495a735b38e..50fa9450fcf1 100644 > --- a/arch/x86/kvm/pmu_amd.c > +++ b/arch/x86/kvm/pmu_amd.c > @@ -269,10 +269,10 @@ static void amd_pmu_refresh(struct kvm_vcpu *vcpu) > > pmu->counter_bitmask[KVM_PMC_GP] = ((u64)1 << 48) - 1; > pmu->reserved_bits = 0xffffffff00200000ull; > + pmu->version = 1; > /* not applicable to AMD; but clean them to prevent any fall out */ > pmu->counter_bitmask[KVM_PMC_FIXED] = 0; > pmu->nr_arch_fixed_counters = 0; > - pmu->version = 0; > pmu->global_status = 0; > } > > -- > 2.21.0 >
