Hi,
On Tue, Feb 11, 2025 at 01:08:52PM +0530, Aneesh Kumar K.V (Arm) wrote:
> Linux kernel documentation states:
>
> "Note! KVM_EXIT_MEMORY_FAULT is unique among all KVM exit reasons in
> that it accompanies a return code of '-1', not '0'! errno will always be
> set to EFAULT or EHWPOISON when KVM exits with KVM_EXIT_MEMORY_FAULT,
> userspace should assume kvm_run.exit_reason is stale/undefined for all
> other error numbers." "
>
> Update the KVM_RUN ioctl error handling to correctly handle
> KVM_EXIT_MEMORY_FAULT.
I've tried to follow how kvmtool handles KVM_EXIT_MEMORY_FAULT before and after
this patch.
Before: calls die_perror().
After: prints more information about the error, in kvm_cpu_thread().
Is that what you want? Because "correctly handle KVM_EXIT_MEMORY_FAULT" can be
interpreted as kvmtool resolving the memory fault, which is something that
kvmtool does not do.
Also, can you update kvm_exit_reasons with KVM_EXIT_MEMORY_FAULT, because
otherwise kvm_cpu_thread() will segfault when it tries to access
kvm_exit_reasons[KVM_EXIT_MEMORY_FAULT].
Thanks,
Alex
>
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@xxxxxxxxxx>
> ---
> kvm-cpu.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/kvm-cpu.c b/kvm-cpu.c
> index 66e30ba54e26..40e4efc33a1d 100644
> --- a/kvm-cpu.c
> +++ b/kvm-cpu.c
> @@ -41,8 +41,15 @@ void kvm_cpu__run(struct kvm_cpu *vcpu)
> return;
>
> err = ioctl(vcpu->vcpu_fd, KVM_RUN, 0);
> - if (err < 0 && (errno != EINTR && errno != EAGAIN))
> - die_perror("KVM_RUN failed");
> + if (err < 0) {
> + if (errno == EINTR || errno == EAGAIN)
> + return;
> + else if (errno == EFAULT &&
> + vcpu->kvm_run->exit_reason == KVM_EXIT_MEMORY_FAULT)
> + return;
> + else
> + die_perror("KVM_RUN failed");
> + }
> }
>
> static void kvm_cpu_signal_handler(int signum)
> --
> 2.43.0
>
>
