[PATCH 06/15] KVM: x86/mmu: Implement PWALK_SET_ACCESSED in page walker

Nikolas Wipper
2024-09-10T15:24:03Z

Implement PWALK_SET_ACCESSED in the page walker. This flag allows
controling whether the page walker will set the accessed bits after a
successful page walk in all page table levels. If the page walk is aborted
for any reason, none of the access bits are set.

Signed-off-by: Nikolas Wipper <nikwip@amazon.de>
---
arch/x86/kvm/mmu/paging_tmpl.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index c278b83b023f..eed6e2c653ba 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -317,6 +317,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
const int write_fault = access & PFERR_WRITE_MASK;
const int user_fault = access & PFERR_USER_MASK;
const int fetch_fault = access & PFERR_FETCH_MASK;
+ const int set_accessed = flags & PWALK_SET_ACCESSED;
u16 errcode = 0;
gpa_t real_gpa;
gfn_t gfn;
@@ -468,7 +469,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
accessed_dirty &= pte >>
(PT_GUEST_DIRTY_SHIFT - PT_GUEST_ACCESSED_SHIFT);

- if (unlikely(!accessed_dirty)) {
+ if (unlikely(set_accessed && !accessed_dirty)) {
ret = FNAME(update_accessed_dirty_bits)(vcpu, mmu, walker, addr,
write_fault);
if (unlikely(ret < 0))