On Fri, Mar 25, 2022, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>
> Let's get the information whether or not guests disable interruptions.
This is missing critical information for _why_. It took me some staring to
understand that this allows querying IRQs from a _different_ vCPU, which needs
caching on VMX due to the need to do a VMREAD.
> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_host.h | 1 +
> arch/x86/kvm/x86.c | 3 +++
> 2 files changed, 4 insertions(+)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 50f011a7445a..8e05cbfa9827 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -861,6 +861,7 @@ struct kvm_vcpu_arch {
> bool preempt_count_enabled;
> struct gfn_to_hva_cache preempt_count_cache;
> } pv_pc;
> + bool irq_disabled;
This is going to at best be confusing, and at worst lead to bugs The flag is
valid if and only if the vCPU is not loaded. I don't have a clever answer, but
this needs to have some form of guard to (a) clarify when it's valid and (b) actively
prevent misuse.
