diff options
| author | Lai Jiangshan <jiangshan.ljs@antgroup.com> | 2023-02-02 18:28:16 +0000 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2023-03-14 10:28:56 -0400 |
| commit | 39fda5d873eb1f59613ce49249ee2effea9f8e06 (patch) | |
| tree | 997fc47924098d5b22390c6facf6b4ae039cdfd3 /arch/x86/kvm/mmu/paging_tmpl.h | |
| parent | 258d985f6eb360c9c7aacd025d0dbc080a59423f (diff) | |
KVM: x86/mmu: Detect write #PF to shadow pages during FNAME(fetch) walk
Move the detection of write #PF to shadow pages, i.e. a fault on a write
to a page table that is being shadowed by KVM that is used to translate
the write itself, from FNAME(is_self_change_mapping) to FNAME(fetch).
There is no need to detect the self-referential write before
kvm_faultin_pfn() as KVM does not consume EMULTYPE_WRITE_PF_TO_SP for
accesses that resolve to "error or no-slot" pfns, i.e. KVM doesn't allow
retrying MMIO accesses or writes to read-only memslots.
Detecting the EMULTYPE_WRITE_PF_TO_SP scenario in FNAME(fetch) will allow
dropping FNAME(is_self_change_mapping) entirely, as the hugepage
interaction can be deferred to kvm_mmu_hugepage_adjust().
Cc: Huang Hang <hhuang@linux.alibaba.com>
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20221213125538.81209-1-jiangshanlai@gmail.com
[sean: split to separate patch, write changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230202182817.407394-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/mmu/paging_tmpl.h')
| -rw-r--r-- | arch/x86/kvm/mmu/paging_tmpl.h | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index 5d2958299b4f..f57d9074fb9b 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -685,6 +685,9 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, if (sp != ERR_PTR(-EEXIST)) link_shadow_page(vcpu, it.sptep, sp); + + if (fault->write && table_gfn == fault->gfn) + fault->write_fault_to_shadow_pgtable = true; } kvm_mmu_hugepage_adjust(vcpu, fault); @@ -741,17 +744,13 @@ out_gpte_changed: * created when kvm establishes shadow page table that stop kvm using large * page size. Do it early can avoid unnecessary #PF and emulation. * - * @write_fault_to_shadow_pgtable will return true if the fault gfn is - * currently used as its page table. - * * Note: the PDPT page table is not checked for PAE-32 bit guest. It is ok * since the PDPT is always shadowed, that means, we can not use large page * size to map the gfn which is used as PDPT. */ static bool FNAME(is_self_change_mapping)(struct kvm_vcpu *vcpu, - struct guest_walker *walker, bool user_fault, - bool *write_fault_to_shadow_pgtable) + struct guest_walker *walker, bool user_fault) { int level; gfn_t mask = ~(KVM_PAGES_PER_HPAGE(walker->level) - 1); @@ -765,7 +764,6 @@ FNAME(is_self_change_mapping)(struct kvm_vcpu *vcpu, gfn_t gfn = walker->gfn ^ walker->table_gfn[level - 1]; self_changed |= !(gfn & mask); - *write_fault_to_shadow_pgtable |= !gfn; } return self_changed; @@ -826,7 +824,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault return r; is_self_change_mapping = FNAME(is_self_change_mapping)(vcpu, - &walker, fault->user, &fault->write_fault_to_shadow_pgtable); + &walker, fault->user); if (is_self_change_mapping) fault->max_level = PG_LEVEL_4K; |