Re: [PATCH v5] KVM: selftests: Test READ=>WRITE dirty logging behavior for shadow MMU

[Sean Christopherson <seanjc@google.com>]

On Thu, Jan 15, 2026, Yosry Ahmed wrote:
> On Thu, Jan 15, 2026 at 09:21:54AM -0800, Sean Christopherson wrote:
> > +static void l2_guest_code(vm_vaddr_t base)
> >  {
> > -	READ_ONCE(*a);
> > -	WRITE_ONCE(*a, 1);
> > -	GUEST_SYNC(true);
> > -	GUEST_SYNC(false);
> > +	vm_vaddr_t page0 = TEST_GUEST_ADDR(base, 0);
> > +	vm_vaddr_t page1 = TEST_GUEST_ADDR(base, 1);
> >  
> > -	WRITE_ONCE(*b, 1);
> > -	GUEST_SYNC(true);
> > -	WRITE_ONCE(*b, 1);
> > -	GUEST_SYNC(true);
> > -	GUEST_SYNC(false);
> > +	READ_ONCE(*(u64 *)page0);
> > +	GUEST_SYNC(page0 | TEST_SYNC_READ_FAULT);
> > +	WRITE_ONCE(*(u64 *)page0, 1);
> > +	GUEST_SYNC(page0 | TEST_SYNC_WRITE_FAULT);
> > +	READ_ONCE(*(u64 *)page0);
> > +	GUEST_SYNC(page0 | TEST_SYNC_NO_FAULT);
> > +
> > +	WRITE_ONCE(*(u64 *)page1, 1);
> > +	GUEST_SYNC(page1 | TEST_SYNC_WRITE_FAULT);
> > +	WRITE_ONCE(*(u64 *)page1, 1);
> > +	GUEST_SYNC(page1 | TEST_SYNC_WRITE_FAULT);
> > +	READ_ONCE(*(u64 *)page1);
> > +	GUEST_SYNC(page1 | TEST_SYNC_NO_FAULT);
> > +	GUEST_SYNC(page1 | TEST_SYNC_NO_FAULT);
> 
> Extra GUEST_SYNC()?

Yeah, I'm guessing it was a copy+paste goof, I can't think of any value added by
a second sync here.  I'll drop it when applying.

Thanks!