This change uses a lighter-weight function instead of mmu_spte_update()
in the common case in spte_write_protect(). This helps speed up the
get_dirty_log IOCTL.
Signed-off-by: Junaid Shahid <junaids@xxxxxxxxxx>
---
arch/x86/kvm/mmu.c | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 4cf43ce42959..189e21c77525 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1460,6 +1460,22 @@ static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
kvm_flush_remote_tlbs(vcpu->kvm);
}
+static bool spte_test_and_clear_writable(u64 *sptep)
+{
+ u64 spte = *sptep;
+
+ if (spte & PT_WRITABLE_MASK) {
+ clear_bit(PT_WRITABLE_SHIFT, (ulong *)sptep);
+
+ if (!spte_ad_enabled(spte))
+ kvm_set_pfn_dirty(spte_to_pfn(spte));
+
+ return true;
+ }
+
+ return false;
+}
+
/*
* Write-protect on the specified @sptep, @pt_protect indicates whether
* spte write-protection is caused by protecting shadow page table.
@@ -1483,11 +1499,12 @@ static bool spte_write_protect(u64 *sptep, bool pt_protect)
rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, *sptep);
- if (pt_protect)
- spte &= ~SPTE_MMU_WRITEABLE;
- spte = spte & ~PT_WRITABLE_MASK;
+ if (pt_protect) {
+ spte &= ~(PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE);
+ return mmu_spte_update(sptep, spte);
+ }
- return mmu_spte_update(sptep, spte);
+ return spte_test_and_clear_writable(sptep);
}
static bool __rmap_write_protect(struct kvm *kvm,
--
2.19.1.568.g152ad8e336-goog
