Re: [PATCH v3] target/arm/kvm: Retry KVM_CREATE_VM call if it fails EINTR

[Marc Zyngier]

On Fri, 30 Sep 2022 12:38:24 +0100,
Peter Maydell <peter.maydell@linaro.org> wrote:
> 
> Occasionally the KVM_CREATE_VM ioctl can return EINTR, even though
> there is no pending signal to be taken. In commit 94ccff13382055
> we added a retry-on-EINTR loop to the KVM_CREATE_VM call in the
> generic KVM code. Adopt the same approach for the use of the
> ioctl in the Arm-specific KVM code (where we use it to create a
> scratch VM for probing for various things).
> 
> For more information, see the mailing list thread:
> https://lore.kernel.org/qemu-devel/8735e0s1zw.wl-maz@kernel.org/
> 
> Reported-by: Vitaly Chikunov <vt@altlinux.org>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> The view in the thread seems to be that this is a kernel bug (because
> in QEMU's case there shouldn't be a signal to be delivered at this
> point because of our signal handling strategy); so I've adopted the
> same "just retry-on-EINTR for this specific ioctl" approach that
> commit 94ccff13 did, rather than, for instance, something wider like
> "make kvm_ioctl() and friends always retry on EINTR".
> 
> v2: correctly check for -1 and errno is EINTR...
> v3: really correctly check errno. This time for sure!
> ---
>  target/arm/kvm.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

Acked-by: Marc Zyngier <maz@kernel.org>

        M.

-- 
Without deviation from the norm, progress is not possible.