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[1/2] KVM: Take mmu_lock only while write-protecting pages in get_dirty_log

Message ID 20130830125121.e8ef36de.yoshikawa_takuya_b1@lab.ntt.co.jp (mailing list archive)
State New, archived
Headers show

Commit Message

Takuya Yoshikawa Aug. 30, 2013, 3:51 a.m. UTC 
Xiao's "KVM: MMU: flush tlb if the spte can be locklessly modified"
allows us to release mmu_lock before flushing TLBs.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
---
 Xiao can change the remaining mmu_lock to RCU's read-side lock:
 The grace period will be reasonably limited.

 arch/x86/kvm/mmu.c |    4 ++++
 arch/x86/kvm/x86.c |    4 ----
 2 files changed, 4 insertions(+), 4 deletions(-)
diff mbox

Patch

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 5d9efb1..c6da9ba 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1249,6 +1249,8 @@  void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
 {
 	unsigned long *rmapp;
 
+	spin_lock(&kvm->mmu_lock);
+
 	while (mask) {
 		rmapp = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask),
 				      PT_PAGE_TABLE_LEVEL, slot);
@@ -1257,6 +1259,8 @@  void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
 		/* clear the first set bit */
 		mask &= mask - 1;
 	}
+
+	spin_unlock(&kvm->mmu_lock);
 }
 
 static bool rmap_write_protect(struct kvm *kvm, u64 gfn)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e5ca72a..1d1f6df 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3543,8 +3543,6 @@  int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
 	dirty_bitmap_buffer = dirty_bitmap + n / sizeof(long);
 	memset(dirty_bitmap_buffer, 0, n);
 
-	spin_lock(&kvm->mmu_lock);
-
 	for (i = 0; i < n / sizeof(long); i++) {
 		unsigned long mask;
 		gfn_t offset;
@@ -3563,8 +3561,6 @@  int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
 	if (is_dirty)
 		kvm_flush_remote_tlbs(kvm);
 
-	spin_unlock(&kvm->mmu_lock);
-
 	r = -EFAULT;
 	if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n))
 		goto out;