From: Kai Huang kai.huang@intel.com
[ Upstream commit 857f84743e4b78500afae010d866675642e18e90 ]
Currently pf_fixed is not increased when prefault is true. This is not correct, since prefault here really means "async page fault completed". In that case, the original page fault from the guest was morphed into as async page fault and pf_fixed was not increased. So when prefault indicates async page fault is completed, pf_fixed should be increased.
Additionally, currently pf_fixed is also increased even when page fault is spurious, while legacy MMU increases pf_fixed when page fault returns RET_PF_EMULATE or RET_PF_FIXED.
To fix above two issues, change to increase pf_fixed when return value is not RET_PF_SPURIOUS (RET_PF_RETRY has already been ruled out by reaching here).
More information: https://lore.kernel.org/kvm/cover.1620200410.git.kai.huang@intel.com/T/#mbb5...
Fixes: bb18842e2111 ("kvm: x86/mmu: Add TDP MMU PF handler") Reviewed-by: Sean Christopherson seanjc@google.com Signed-off-by: Kai Huang kai.huang@intel.com Message-Id: 2ea8b7f5d4f03c99b32bc56fc982e1e4e3d3fc6b.1623717884.git.kai.huang@intel.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kvm/mmu/tdp_mmu.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 35b0ece7beff..8773bd5287da 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -949,7 +949,11 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu, int write, rcu_dereference(iter->sptep)); }
- if (!prefault) + /* + * Increase pf_fixed in both RET_PF_EMULATE and RET_PF_FIXED to be + * consistent with legacy MMU behavior. + */ + if (ret != RET_PF_SPURIOUS) vcpu->stat.pf_fixed++;
return ret;