[PATCH 4/9] KVM: MMU: cleanup __kvm_sync_page and its callers

From: Paolo Bonzini
Date: Wed Feb 24 2016 - 04:28:01 EST


Calling kvm_unlink_unsync_page in the middle of __kvm_sync_page makes
things unnecessarily tricky. If kvm_mmu_prepare_zap_page is called,
it will call kvm_unlink_unsync_page too. So kvm_unlink_unsync_page can
be called just as well at the beginning or the end of __kvm_sync_page...
which means that we might do it in kvm_sync_page too and remove the
parameter.

kvm_sync_page ends up being the same code that kvm_sync_pages used
to have before the previous patch.

Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/mmu.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 56be33714036..88a1a79c869e 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1917,16 +1917,13 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,

/* @sp->gfn should be write-protected at the call site */
static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
- struct list_head *invalid_list, bool clear_unsync)
+ struct list_head *invalid_list)
{
if (sp->role.cr4_pae != !!is_pae(vcpu)) {
kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
return 1;
}

- if (clear_unsync)
- kvm_unlink_unsync_page(vcpu->kvm, sp);
-
if (vcpu->arch.mmu.sync_page(vcpu, sp)) {
kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
return 1;
@@ -1956,7 +1953,7 @@ static int kvm_sync_page_transient(struct kvm_vcpu *vcpu,
LIST_HEAD(invalid_list);
int ret;

- ret = __kvm_sync_page(vcpu, sp, &invalid_list, false);
+ ret = __kvm_sync_page(vcpu, sp, &invalid_list);
kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, !ret);

return ret;
@@ -1972,7 +1969,8 @@ static void mmu_audit_disable(void) { }
static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
struct list_head *invalid_list)
{
- return __kvm_sync_page(vcpu, sp, invalid_list, true);
+ kvm_unlink_unsync_page(vcpu->kvm, sp);
+ return __kvm_sync_page(vcpu, sp, invalid_list);
}

/* @gfn should be write-protected at the call site */
--
1.8.3.1