Re: [PATCH v10 5/9] KVM: Use gfn instead of hva for mmu_notifier_retry

On Tue, Dec 06, 2022 at 10:34:11PM -0800, Isaku Yamahata wrote:

On Tue, Dec 06, 2022 at 07:56:23PM +0800,
Chao Peng [off-list ref] wrote:

quoted

quoted

quoted

-       if (unlikely(kvm->mmu_invalidate_in_progress) &&
-           hva >= kvm->mmu_invalidate_range_start &&
-           hva < kvm->mmu_invalidate_range_end)
-               return 1;
+       if (unlikely(kvm->mmu_invalidate_in_progress)) {
+               /*
+                * Dropping mmu_lock after bumping mmu_invalidate_in_progress
+                * but before updating the range is a KVM bug.
+                */
+               if (WARN_ON_ONCE(kvm->mmu_invalidate_range_start == INVALID_GPA ||
+                                kvm->mmu_invalidate_range_end == INVALID_GPA))

INVALID_GPA is an x86-specific define in
arch/x86/include/asm/kvm_host.h, so this doesn't build on other
architectures. The obvious fix is to move it to
include/linux/kvm_host.h.

Hmm, INVALID_GPA is defined as ZERO for x86, not 100% confident this is
correct choice for other architectures, but after search it has not been
used for other architectures, so should be safe to make it common.

INVALID_GPA is defined as all bit 1.  Please notice "~" (tilde).

#define INVALID_GPA (~(gpa_t)0)

Thanks for mention. Still looks right moving it to include/linux/kvm_host.h. 
Chao

-- 
Isaku Yamahata [off-list ref]