KVM: Flush remote tlbs when reducing shadow pte permissions

When a vcpu causes a shadow tlb entry to have reduced permissions, it
must also clear the tlb on remote vcpus.  We do that by:

- setting a bit on the vcpu that requests a tlb flush before the next entry
- if the vcpu is currently executing, we send an ipi to make sure it
  exits before we continue

Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 15 insertions, 7 deletions

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index a1f51b9d482d..b969db1e0830 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1972,6 +1972,11 @@ static int dm_request_for_irq_injection(struct kvm_vcpu *vcpu,
                 (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF));
 }
 
+static void vmx_flush_tlb(struct kvm_vcpu *vcpu)
+{
+        vmcs_writel(GUEST_CR3, vmcs_readl(GUEST_CR3));
+}
+
 static int vmx_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 {
         u8 fail;
@@ -1997,9 +2002,15 @@ again:
          */
         vmcs_writel(HOST_CR0, read_cr0());
 
+        local_irq_disable();
+
+        vcpu->guest_mode = 1;
+        if (vcpu->requests)
+                if (test_and_clear_bit(KVM_TLB_FLUSH, &vcpu->requests))
+                    vmx_flush_tlb(vcpu);
+
         asm (
                 /* Store host registers */
-                "pushf \n\t"
 #ifdef CONFIG_X86_64
                 "push %%rax; push %%rbx; push %%rdx;"
                 "push %%rsi; push %%rdi; push %%rbp;"
@@ -2091,7 +2102,6 @@ again:
                 "pop %%ecx; popa \n\t"
 #endif
                 "setbe %0 \n\t"
-                "popf \n\t"
               : "=q" (fail)
               : "r"(vcpu->launched), "d"((unsigned long)HOST_RSP),
                 "c"(vcpu),
@@ -2115,6 +2125,9 @@ again:
                 [cr2]"i"(offsetof(struct kvm_vcpu, cr2))
               : "cc", "memory" );
 
+        vcpu->guest_mode = 0;
+        local_irq_enable();
+
         ++vcpu->stat.exits;
 
         vcpu->interrupt_window_open = (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & 3) == 0;
@@ -2167,11 +2180,6 @@ out:
         return r;
 }
 
-static void vmx_flush_tlb(struct kvm_vcpu *vcpu)
-{
-        vmcs_writel(GUEST_CR3, vmcs_readl(GUEST_CR3));
-}
-
 static void vmx_inject_page_fault(struct kvm_vcpu *vcpu,
                                   unsigned long addr,
                                   u32 err_code)