On 03/07/21 00:04, isaku.yamahata@xxxxxxxxx wrote:
From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Return the old SPTE when clearing a SPTE and push the "old SPTE present"
check to the caller. Private shadow page support will use the old SPTE
in rmap_remove() to determine whether or not there is a linked private
shadow page.
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 0259781cee6a..6b0c8c84aabe 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -542,9 +542,9 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte)
* Rules for using mmu_spte_clear_track_bits:
* It sets the sptep from present to nonpresent, and track the
* state bits, it is used to clear the last level sptep.
- * Returns non-zero if the PTE was previously valid.
+ * Returns the old PTE.
*/
-static int mmu_spte_clear_track_bits(u64 *sptep)
+static u64 mmu_spte_clear_track_bits(u64 *sptep)
{
kvm_pfn_t pfn;
u64 old_spte = *sptep;
@@ -555,7 +555,7 @@ static int mmu_spte_clear_track_bits(u64 *sptep)
old_spte = __update_clear_spte_slow(sptep, shadow_init_value);
if (!is_shadow_present_pte(old_spte))
- return 0;
+ return old_spte;
pfn = spte_to_pfn(old_spte);
@@ -572,7 +572,7 @@ static int mmu_spte_clear_track_bits(u64 *sptep)
if (is_dirty_spte(old_spte))
kvm_set_pfn_dirty(pfn);
- return 1;
+ return old_spte;
}
/*
@@ -1104,7 +1104,9 @@ static u64 *rmap_get_next(struct rmap_iterator *iter)
static void drop_spte(struct kvm *kvm, u64 *sptep)
{
- if (mmu_spte_clear_track_bits(sptep))
+ u64 old_spte = mmu_spte_clear_track_bits(sptep);
+
+ if (is_shadow_present_pte(old_spte))
rmap_remove(kvm, sptep);
}
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
