Re: [RFC PATCH V4 13/17] x86/sev: Add Check of #HV event in path

[Tianyu Lan]

On 4/14/2023 7:02 PM, Pankaj Gupta wrote:
> > +void check_hv_pending_irq_enable(void)
> > +{
> > +       struct pt_regs regs;
> > +
> > +       if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
> > +               return;
> > +
> > +       memset(&regs, 0, sizeof(struct pt_regs));
> > +       asm volatile("movl %%cs, %%eax;" : "=a" (regs.cs));
> > +       asm volatile("movl %%ss, %%eax;" : "=a" (regs.ss));
> > +       regs.orig_ax = 0xffffffff;
> > +       regs.flags = native_save_fl();
> > +
> > +       /*
> > +        * Disable irq when handle pending #HV events after
> > +        * re-enabling irq.
> > +        */
> > +       asm volatile("cli" : : : "memory");
> Just curious, Does the hypervisor injects irqs via doorbell page when
> interrupts are disabled with "cli" ? Trying to understand the need to
> cli/sti covering on "do_exc_hv".


Hi Pankaj:
	Thanks for your review. Yes, Hypervisor still injects #HV exception 
when irq was disabled check_hv_pending() is called when
there is a #HV exception. It checks irq flag and return back without 
handling irq event when irq was disabled.