[PATCH 24/24] kvm: x86/mmu: Allow parallel page faults for the TDP MMU

Ben Gardon
2021-01-12T18:13:21Z

Make the last few changes necessary to enable the TDP MMU to handle page
faults in parallel while holding the mmu_lock in read mode.

Reviewed-by: Peter Feiner <pfeiner@google.com>

Signed-off-by: Ben Gardon <bgardon@google.com>
---
arch/x86/kvm/mmu/mmu.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 280d7cd6f94b..fa111ceb67d4 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3724,7 +3724,12 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
return r;

r = RET_PF_RETRY;
- kvm_mmu_lock(vcpu->kvm);
+
+ if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa))
+ kvm_mmu_lock_shared(vcpu->kvm);
+ else
+ kvm_mmu_lock(vcpu->kvm);
+
if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
goto out_unlock;
r = make_mmu_pages_available(vcpu);
@@ -3739,7 +3744,10 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
prefault, is_tdp);

out_unlock:
- kvm_mmu_unlock(vcpu->kvm);
+ if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa))
+ kvm_mmu_unlock_shared(vcpu->kvm);
+ else
+ kvm_mmu_unlock(vcpu->kvm);
kvm_release_pfn_clean(pfn);
return r;
}
--
2.30.0.284.gd98b1dd5eaa7-goog