This mainly indicates to KVM that it should expect all private guest
memory to be backed by private memslots. Ideally this would work
similarly for others archs, give or take a few additional flags, but
for now it's a simple boolean indicator for x86.
Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 3 +++
arch/x86/kvm/x86.c | 10 ++++++++++
include/uapi/linux/kvm.h | 1 +
3 files changed, 14 insertions(+)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 27ef31133352..2b6244525107 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1438,6 +1438,9 @@ struct kvm_arch {
*/
#define SPLIT_DESC_CACHE_MIN_NR_OBJECTS (SPTE_ENT_PER_PAGE + 1)
struct kvm_mmu_memory_cache split_desc_cache;
+
+ /* Use/enforce unmapped private memory. */
+ bool upm_mode;
};
struct kvm_vm_stat {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c67e22f3e2ee..99ecf99bc4d2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4421,6 +4421,11 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_EXIT_HYPERCALL:
r = KVM_EXIT_HYPERCALL_VALID_MASK;
break;
+#ifdef CONFIG_HAVE_KVM_MEMORY_ATTRIBUTES
+ case KVM_CAP_UNMAPPED_PRIVATE_MEM:
+ r = 1;
+ break;
+#endif
case KVM_CAP_SET_GUEST_DEBUG2:
return KVM_GUESTDBG_VALID_MASK;
#ifdef CONFIG_KVM_XEN
@@ -6382,6 +6387,10 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
}
mutex_unlock(&kvm->lock);
break;
+ case KVM_CAP_UNMAPPED_PRIVATE_MEM:
+ kvm->arch.upm_mode = true;
+ r = 0;
+ break;
default:
r = -EINVAL;
break;
@@ -12128,6 +12137,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
kvm->arch.default_tsc_khz = max_tsc_khz ? : tsc_khz;
kvm->arch.guest_can_read_msr_platform_info = true;
kvm->arch.enable_pmu = enable_pmu;
+ kvm->arch.upm_mode = false;
#if IS_ENABLED(CONFIG_HYPERV)
spin_lock_init(&kvm->arch.hv_root_tdp_lock);
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index c7e9d375a902..cc9424ccf9b2 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1219,6 +1219,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_DIRTY_LOG_RING_ACQ_REL 223
#define KVM_CAP_S390_PROTECTED_ASYNC_DISABLE 224
#define KVM_CAP_MEMORY_ATTRIBUTES 225
+#define KVM_CAP_UNMAPPED_PRIVATE_MEM 240
#ifdef KVM_CAP_IRQ_ROUTING
--
2.25.1
