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Subject[PATCH v5 4/9] KVM: MMU: fold tlb flush judgement into mmu_spte_update
mmu_spte_update() is the common function, we can easily audit the path

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
---
arch/x86/kvm/mmu.c | 33 ++++++++++++++++++++-------------
1 files changed, 20 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 337ff0a..4810992 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -478,15 +478,24 @@ static void mmu_spte_set(u64 *sptep, u64 new_spte)

/* Rules for using mmu_spte_update:
* Update the state bits, it means the mapped pfn is not changged.
+ *
+ * Whenever we overwrite a writable spte with a read-only one we
+ * should flush remote TLBs. Otherwise rmap_write_protect
+ * will find a read-only spte, even though the writable spte
+ * might be cached on a CPU's TLB, the return value indicates this
+ * case.
*/
-static void mmu_spte_update(u64 *sptep, u64 new_spte)
+static bool mmu_spte_update(u64 *sptep, u64 new_spte)
{
u64 mask, old_spte = *sptep;
+ bool ret = false;

WARN_ON(!is_rmap_spte(new_spte));

- if (!is_shadow_present_pte(old_spte))
- return mmu_spte_set(sptep, new_spte);
+ if (!is_shadow_present_pte(old_spte)) {
+ mmu_spte_set(sptep, new_spte);
+ return ret;
+ }

new_spte |= old_spte & shadow_dirty_mask;

@@ -499,13 +508,18 @@ static void mmu_spte_update(u64 *sptep, u64 new_spte)
else
old_spte = __update_clear_spte_slow(sptep, new_spte);

+ if (is_writable_pte(old_spte) && !is_writable_pte(new_spte))
+ ret = true;
+
if (!shadow_accessed_mask)
- return;
+ return ret;

if (spte_is_bit_cleared(old_spte, new_spte, shadow_accessed_mask))
kvm_set_pfn_accessed(spte_to_pfn(old_spte));
if (spte_is_bit_cleared(old_spte, new_spte, shadow_dirty_mask))
kvm_set_pfn_dirty(spte_to_pfn(old_spte));
+
+ return ret;
}

/*
@@ -2256,7 +2270,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
gfn_t gfn, pfn_t pfn, bool speculative,
bool can_unsync, bool host_writable)
{
- u64 spte, entry = *sptep;
+ u64 spte;
int ret = 0;

if (set_mmio_spte(sptep, gfn, pfn, pte_access))
@@ -2334,14 +2348,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
mark_page_dirty(vcpu->kvm, gfn);

set_pte:
- mmu_spte_update(sptep, spte);
- /*
- * If we overwrite a writable spte with a read-only one we
- * should flush remote TLBs. Otherwise rmap_write_protect
- * will find a read-only spte, even though the writable spte
- * might be cached on a CPU's TLB.
- */
- if (is_writable_pte(entry) && !is_writable_pte(*sptep))
+ if (mmu_spte_update(sptep, spte))
kvm_flush_remote_tlbs(vcpu->kvm);
done:
return ret;
--
1.7.7.6


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