Re: KVM Kernel 5.6+, BUG: stack guard page was hit at

["Boris V." <borisvk@bstnet.org>]

On 2020-04-23 13:54, Suravee Suthikulpanit wrote:
> Boris,
>
> On 4/22/20 12:43 PM, Boris V. wrote:
>> Hello,
>>
>> when running qemu with GPU passthrough it crashes with 5.6 and also 
>> 5.7-rc kernels, it works with 5.5 and lower.
>> Without GPU passthrough I don't see this crash.
>> With bisecting, I found commit that causes this BUG.
>> It seems bad commit is f458d039db7e8518041db4169d657407e3217008, if I 
>> revert this patch it works.
>
> Could you please try the following patch?
>
> Thanks,
> Suravee
>
> --- BEGIN PATCH ---
> commit 5a605d65a71583195f64d42f39a29c771e2c763a
> Author: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> Date:   Thu Apr 23 06:40:11 2020 -0500
>
>     kvm: ioapic: Introduce arch-specific check for lazy update EOI 
> mechanism
>
>     commit f458d039db7e ("kvm: ioapic: Lazy update IOAPIC EOI") 
> introduces
>     a regression on Intel VMX APICv since it always force IOAPIC lazy 
> update
>     EOI mechanism when APICv is activated, which is needed to support AMD
>     SVM AVIC.
>
>     Fixes by introducing struct kvm_arch.use_lazy_eoi variable to specify
>     whether the architecture needs lazy update EOI support.
>
>     Fixes: f458d039db7e ("kvm: ioapic: Lazy update IOAPIC EOI")
>     Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> ---
>  arch/x86/include/asm/kvm_host.h | 2 ++
>  arch/x86/kvm/ioapic.c           | 3 +++
>  arch/x86/kvm/svm.c              | 1 +
>  3 files changed, 6 insertions(+)
>

Yes, this this patch works, there is no longer kernel BUG.

Thanks,
Boris