When the memslot flag is enabled, fail guest memory accesses for which
fast-gup fails (ie, where resolving the page fault would require putting
the faulting thread to sleep).
Suggested-by: James Houghton <jthoughton@xxxxxxxxxx>
Signed-off-by: Anish Moorthy <amoorthy@xxxxxxxxxx>
---
Documentation/virt/kvm/api.rst | 2 +-
arch/x86/kvm/mmu/mmu.c | 17 ++++++++++++-----
arch/x86/kvm/x86.c | 1 +
3 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 9daadbe2c7ed..aa7b4024fd41 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -7783,7 +7783,7 @@ bugs and reported to the maintainers so that annotations can be added.
7.35 KVM_CAP_NOWAIT_ON_FAULT
----------------------------
-:Architectures: None
+:Architectures: x86
:Returns: -EINVAL.
The presence of this capability indicates that userspace may pass the
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index cb71aae9aaec..288008a64e5c 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4299,7 +4299,9 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work)
kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, 0, true, NULL);
}
-static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
+static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu,
+ struct kvm_page_fault *fault,
+ bool nowait)
{
struct kvm_memory_slot *slot = fault->slot;
bool async;
@@ -4332,9 +4334,12 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
}
async = false;
- fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, false, &async,
- fault->write, &fault->map_writable,
- &fault->hva);
+
+ fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn,
+ nowait, false,
+ nowait ? NULL : &async,
+ fault->write, &fault->map_writable, &fault->hva);
+
if (!async)
return RET_PF_CONTINUE; /* *pfn has correct page already */
@@ -4368,7 +4373,9 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
fault->mmu_seq = vcpu->kvm->mmu_invalidate_seq;
smp_rmb();
- ret = __kvm_faultin_pfn(vcpu, fault);
+ ret = __kvm_faultin_pfn(vcpu, fault,
+ likely(fault->slot)
+ && kvm_slot_nowait_on_fault(fault->slot));
if (ret != RET_PF_CONTINUE)
return ret;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d15bacb3f634..4fbe9c811cc7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4498,6 +4498,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_VM_DISABLE_NX_HUGE_PAGES:
case KVM_CAP_IRQFD_RESAMPLE:
case KVM_CAP_MEMORY_FAULT_INFO:
+ case KVM_CAP_NOWAIT_ON_FAULT:
r = 1;
break;
case KVM_CAP_EXIT_HYPERCALL:
--
2.41.0.rc0.172.g3f132b7071-goog
