From: Borislav Petkov <[email protected]>
After commit:
672ff6cff80c ("KVM: x86: Raise #GP when guest vCPU do not support PMU")
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
On Wed, May 08, 2019 at 05:08:44PM +0000, Lendacky, Thomas wrote:
> 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.
Paolo, Radim, can you do that pls, when applying?
Thx.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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
>
On 08/05/19 19:14, Borislav Petkov wrote:
> On Wed, May 08, 2019 at 05:08:44PM +0000, Lendacky, Thomas wrote:
>> 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.
>
> Paolo, Radim, can you do that pls, when applying?
Yes, done (and queued the patch).
Paolo