Nove the kvm_unlink_unsync_page() call out of kvm_sync_page() and into
it's sole caller, and fold __kvm_sync_page() into kvm_sync_page() since
the latter becomes a pure pass-through. There really should be no reason
for code to do a complete sync of a shadow page outside of the full
kvm_mmu_sync_roots(), e.g. the one use case that creeped in turned out to
be flawed and counter-productive.
Update the comment in kvm_mmu_get_page() regarding its sync_page() usage,
which is anything but obvious.
Drop the stale comment about @sp->gfn needing to be write-protected, as
it directly contradicts the kvm_mmu_get_page() usage.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 36 +++++++++++++++++++-----------------
1 file changed, 19 insertions(+), 17 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 2e2d66319325..77296ce6215f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1780,18 +1780,6 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,
&(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)]) \
if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else
-/* @sp->gfn should be write-protected at the call site */
-static bool __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
- struct list_head *invalid_list)
-{
- if (vcpu->arch.mmu->sync_page(vcpu, sp) == 0) {
- kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
- return false;
- }
-
- return true;
-}
-
static bool kvm_mmu_remote_flush_or_zap(struct kvm *kvm,
struct list_head *invalid_list,
bool remote_flush)
@@ -1833,8 +1821,12 @@ static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
struct list_head *invalid_list)
{
- kvm_unlink_unsync_page(vcpu->kvm, sp);
- return __kvm_sync_page(vcpu, sp, invalid_list);
+ if (vcpu->arch.mmu->sync_page(vcpu, sp) == 0) {
+ kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
+ return false;
+ }
+
+ return true;
}
struct mmu_page_path {
@@ -1931,6 +1923,7 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu,
}
for_each_sp(pages, sp, parents, i) {
+ kvm_unlink_unsync_page(vcpu->kvm, sp);
flush |= kvm_sync_page(vcpu, sp, &invalid_list);
mmu_pages_clear_parents(&parents);
}
@@ -2008,10 +2001,19 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
goto trace_get_page;
if (sp->unsync) {
- /* The page is good, but __kvm_sync_page might still end
- * up zapping it. If so, break in order to rebuild it.
+ /*
+ * The page is good, but is stale. "Sync" the page to
+ * get the latest guest state, but don't write-protect
+ * the page and don't mark it synchronized! KVM needs
+ * to ensure the mapping is valid, but doesn't need to
+ * fully sync (write-protect) the page until the guest
+ * invalidates the TLB mapping. This allows multiple
+ * SPs for a single gfn to be unsync.
+ *
+ * If the sync fails, the page is zapped. If so, break
+ * If so, break in order to rebuild it.
*/
- if (!__kvm_sync_page(vcpu, sp, &invalid_list))
+ if (!kvm_sync_page(vcpu, sp, &invalid_list))
break;
WARN_ON(!list_empty(&invalid_list));
--
2.32.0.288.g62a8d224e6-goog
