Re: [PATCH] KVM: x86: use positive error values for msr emulation that causes #GP

[Qian Cai]

On Sun, 2020-11-01 at 13:55 +0200, Maxim Levitsky wrote:
> Recent introduction of the userspace msr filtering added code that uses
> negative error codes for cases that result in either #GP delivery to
> the guest, or handled by the userspace msr filtering.
> 
> This breaks an assumption that a negative error code returned from the
> msr emulation code is a semi-fatal error which should be returned
> to userspace via KVM_RUN ioctl and usually kill the guest.
> 
> Fix this by reusing the already existing KVM_MSR_RET_INVALID error code,
> and by adding a new KVM_MSR_RET_FILTERED error code for the
> userspace filtered msrs.
> 
> Fixes: 291f35fb2c1d1 ("KVM: x86: report negative values from wrmsr emulation
> to userspace")
> Reported-by: Qian Cai <cai@xxxxxxxxxx>
> Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Apparently, it does not apply cleanly on today's linux-next. Paolo, is it
possible to toss this into -next soon, so our CI won't be blocked because of
this bug?