[PATCH] KVM: add KVM_SYNC_SHADOW_WITH_USER ioctl

[Marcelo Tosatti <marcelo-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>]

The host needs to zap its shadow entries before performing an inflate
operation to avoid the guest from using stale ones.

So add an ioctl to interface with kvm_mmu_zap_all().

Signed-off-by: Marcelo Tosatti <mtosatti-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

Index: kvm.quilt/arch/x86/kvm/x86.c
===================================================================
--- kvm.quilt.orig/arch/x86/kvm/x86.c
+++ kvm.quilt/arch/x86/kvm/x86.c
@@ -680,6 +680,7 @@ int kvm_dev_ioctl_check_extension(long e
 	case KVM_CAP_USER_MEMORY:
 	case KVM_CAP_SET_TSS_ADDR:
 	case KVM_CAP_EXT_CPUID:
+	case KVM_CAP_SYNC_SHADOW_WITH_USER:
 		r = 1;
 		break;
 	case KVM_CAP_VAPIC:
Index: kvm.quilt/include/linux/kvm.h
===================================================================
--- kvm.quilt.orig/include/linux/kvm.h
+++ kvm.quilt/include/linux/kvm.h
@@ -249,6 +249,7 @@ struct kvm_vapic_addr {
 #define KVM_CAP_SET_TSS_ADDR 4
 #define KVM_CAP_EXT_CPUID 5
 #define KVM_CAP_VAPIC 6
+#define KVM_CAP_SYNC_SHADOW_WITH_USER 7
 
 /*
  * ioctls for VM fds
@@ -267,6 +268,7 @@ struct kvm_vapic_addr {
 #define KVM_GET_DIRTY_LOG         _IOW(KVMIO, 0x42, struct kvm_dirty_log)
 #define KVM_SET_MEMORY_ALIAS      _IOW(KVMIO, 0x43, struct kvm_memory_alias)
 #define KVM_GET_SUPPORTED_CPUID   _IOWR(KVMIO, 0x48, struct kvm_cpuid2)
+#define KVM_SYNC_SHADOW_WITH_USER _IO(KVMIO, 0x49)
 /* Device model IOC */
 #define KVM_CREATE_IRQCHIP	  _IO(KVMIO,  0x60)
 #define KVM_IRQ_LINE		  _IOW(KVMIO, 0x61, struct kvm_irq_level)
Index: kvm.quilt/virt/kvm/kvm_main.c
===================================================================
--- kvm.quilt.orig/virt/kvm/kvm_main.c
+++ kvm.quilt/virt/kvm/kvm_main.c
@@ -971,6 +971,11 @@ static long kvm_vm_ioctl(struct file *fi
 			goto out;
 		break;
 	}
+	case KVM_SYNC_SHADOW_WITH_USER: {
+		r = 0;
+		kvm_mmu_zap_all(kvm);
+		break;
+	}
 	default:
 		r = kvm_arch_vm_ioctl(filp, ioctl, arg);
 	}


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