Modify the page fault path to meet the direct build EPT requirement
RFC 5/9 Modify the page fault path to meet the direct build EPT requirement
From: Yulei Zhang <[email protected]>
Refine the fast page fault code so that it can be used in either normal ept mode or direct build EPT mode.
Signed-off-by Yulei Zhang <[email protected]>
--- arch/x86/kvm/mmu/mmu.c | 30 +++++++++++++++++++++--------- 1 file changed, 21 insertions(+), 9 deletions(-)
arch/x86/kvm/mmu/mmu.c +21 -9
@@ -3471,12 +3471,13 @@ static bool page_fault_can_be_fast(u32 error_code)* someone else modified the SPTE from its original value. */ static bool -fast_pf_fix_direct_spte (struct kvm_vcpu *vcpu,struct kvm_mmu_page *sp, +fast_pf_fix_direct_spte (struct kvm_vcpu *vcpu,gpa_t gpa,u64 *sptep,u64 old_spte,u64 new_spte) {gfn_t gfn; -WARN_ON (!sp->role.direct); +WARN_ON (!vcpu->arch.direct_build_tdp && + (!page_header (__pa (sptep))->role.direct));/* * Theoretically we could also set dirty bit (and flush TLB) here in
@@ -3498,7 +3499,7 @@ fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,* The gfn of direct spte is stable since it is * calculated by sp->gfn. */ - gfn =kvm_mmu_page_get_gfn (sp, sptep - sp->spt); + gfn = gpa >>PAGE_SHIFT ;kvm_vcpu_mark_page_dirty (vcpu, gfn); }
@@ -3526,10 +3527,10 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u32 error_code) {struct kvm_shadow_walk_iterator iterator; -struct kvm_mmu_page *sp;bool fault_handled = false;u64 spte =0ull ;uint retry_count =0 ; +int pte_level =0 ;if (!page_fault_can_be_fast (error_code))return false;
@@ -3539,12 +3540,20 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, do { u64 new_spte; - for_each_shadow_entry_lockless(vcpu, cr2_or_gpa, iterator, spte) + for_each_shadow_entry_lockless(vcpu, cr2_or_gpa, iterator, spte) { if (!is_shadow_present_pte(spte)) break; + } + + if (iterator.level < PT_PAGE_TABLE_LEVEL) + pte_level = PT_PAGE_TABLE_LEVEL; + else + pte_level = iterator.level; + + WARN_ON(!vcpu->arch.direct_build_tdp && + (pte_level != page_header(__pa(iterator.sptep))->role.level)); - sp = page_header(__pa(iterator.sptep)); - if (!is_last_spte(spte, sp->role.level)) + if (!is_last_spte(spte, pte_level)) break; /*
@@ -3587,7 +3596,7 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,* * See the comments in kvm_arch_commit_memory_region(). */ -if (sp->role.level >PT_PAGE_TABLE_LEVEL ) +if (pte_level >PT_PAGE_TABLE_LEVEL )break ; }
@@ -3601,7 +3610,7 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,* since the gfn is not stable for indirect shadow page. See * Documentation/virt/kvm/locking.txt to get more detail. */ - fault_handled =fast_pf_fix_direct_spte (vcpu, sp, + fault_handled =fast_pf_fix_direct_spte (vcpu, cr2_or_gpa, iterator.sptep, spte, new_spte);if (fault_handled)
@@ -4153,6 +4162,9 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,if (fast_page_fault (vcpu, gpa, error_code))return RET_PF_RETRY ; +if (vcpu->arch.direct_build_tdp) +return RET_PF_EMULATE ; + mmu_seq = vcpu->kvm->mmu_notifier_seq;smp_rmb ();
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2.17.1