| Message ID | 20230718234512.1690985-15-seanjc@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: guest_memfd() and per-page attributes | expand |
On 7/19/23 01:44, Sean Christopherson wrote: > From: Chao Peng <chao.p.peng@linux.intel.com> > > A KVM_MEM_PRIVATE memslot can include both fd-based private memory and > hva-based shared memory. Architecture code (like TDX code) can tell > whether the on-going fault is private or not. This patch adds a > 'is_private' field to kvm_page_fault to indicate this and architecture > code is expected to set it. > > To handle page fault for such memslot, the handling logic is different > depending on whether the fault is private or shared. KVM checks if > 'is_private' matches the host's view of the page (maintained in > mem_attr_array). > - For a successful match, private pfn is obtained with > restrictedmem_get_page() and shared pfn is obtained with existing > get_user_pages(). > - For a failed match, KVM causes a KVM_EXIT_MEMORY_FAULT exit to > userspace. Userspace then can convert memory between private/shared > in host's view and retry the fault. > > Co-developed-by: Yu Zhang <yu.c.zhang@linux.intel.com> > Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com> > Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com> > Reviewed-by: Fuad Tabba <tabba@google.com> > Tested-by: Fuad Tabba <tabba@google.com> > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/kvm/mmu/mmu.c | 82 +++++++++++++++++++++++++++++++-- > arch/x86/kvm/mmu/mmu_internal.h | 3 ++ > arch/x86/kvm/mmu/mmutrace.h | 1 + > 3 files changed, 81 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index aefe67185637..4cf73a579ee1 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -3179,9 +3179,9 @@ static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, > return level; > } > > -int kvm_mmu_max_mapping_level(struct kvm *kvm, > - const struct kvm_memory_slot *slot, gfn_t gfn, > - int max_level) > +static int __kvm_mmu_max_mapping_level(struct kvm *kvm, > + const struct kvm_memory_slot *slot, > + gfn_t gfn, int max_level, bool is_private) > { > struct kvm_lpage_info *linfo; > int host_level; > @@ -3193,6 +3193,9 @@ int kvm_mmu_max_mapping_level(struct kvm *kvm, > break; > } > > + if (is_private) > + return max_level; > + > if (max_level == PG_LEVEL_4K) > return PG_LEVEL_4K; > > @@ -3200,6 +3203,16 @@ int kvm_mmu_max_mapping_level(struct kvm *kvm, > return min(host_level, max_level); > } > > +int kvm_mmu_max_mapping_level(struct kvm *kvm, > + const struct kvm_memory_slot *slot, gfn_t gfn, > + int max_level) > +{ > + bool is_private = kvm_slot_can_be_private(slot) && > + kvm_mem_is_private(kvm, gfn); > + > + return __kvm_mmu_max_mapping_level(kvm, slot, gfn, max_level, is_private); > +} > + > void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) > { > struct kvm_memory_slot *slot = fault->slot; > @@ -3220,8 +3233,9 @@ void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > * Enforce the iTLB multihit workaround after capturing the requested > * level, which will be used to do precise, accurate accounting. > */ > - fault->req_level = kvm_mmu_max_mapping_level(vcpu->kvm, slot, > - fault->gfn, fault->max_level); > + fault->req_level = __kvm_mmu_max_mapping_level(vcpu->kvm, slot, > + fault->gfn, fault->max_level, > + fault->is_private); > if (fault->req_level == PG_LEVEL_4K || fault->huge_page_disallowed) > return; > > @@ -4304,6 +4318,55 @@ 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 inline u8 kvm_max_level_for_order(int order) > +{ > + BUILD_BUG_ON(KVM_MAX_HUGEPAGE_LEVEL > PG_LEVEL_1G); > + > + MMU_WARN_ON(order != KVM_HPAGE_GFN_SHIFT(PG_LEVEL_1G) && > + order != KVM_HPAGE_GFN_SHIFT(PG_LEVEL_2M) && > + order != KVM_HPAGE_GFN_SHIFT(PG_LEVEL_4K)); > + > + if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_1G)) > + return PG_LEVEL_1G; > + > + if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_2M)) > + return PG_LEVEL_2M; > + > + return PG_LEVEL_4K; > +} > + > +static int kvm_do_memory_fault_exit(struct kvm_vcpu *vcpu, > + struct kvm_page_fault *fault) > +{ > + vcpu->run->exit_reason = KVM_EXIT_MEMORY_FAULT; > + if (fault->is_private) > + vcpu->run->memory.flags = KVM_MEMORY_EXIT_FLAG_PRIVATE; > + else > + vcpu->run->memory.flags = 0; > + vcpu->run->memory.gpa = fault->gfn << PAGE_SHIFT; > + vcpu->run->memory.size = PAGE_SIZE; > + return RET_PF_USER; > +} > + > +static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu, > + struct kvm_page_fault *fault) > +{ > + int max_order, r; > + > + if (!kvm_slot_can_be_private(fault->slot)) > + return kvm_do_memory_fault_exit(vcpu, fault); > + > + r = kvm_gmem_get_pfn(vcpu->kvm, fault->slot, fault->gfn, &fault->pfn, > + &max_order); > + if (r) > + return r; > + > + fault->max_level = min(kvm_max_level_for_order(max_order), > + fault->max_level); > + fault->map_writable = !(fault->slot->flags & KVM_MEM_READONLY); > + return RET_PF_CONTINUE; > +} > + > static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) > { > struct kvm_memory_slot *slot = fault->slot; > @@ -4336,6 +4399,12 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > return RET_PF_EMULATE; > } > > + if (fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) > + return kvm_do_memory_fault_exit(vcpu, fault); > + > + if (fault->is_private) > + return kvm_faultin_pfn_private(vcpu, fault); > + > async = false; > fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, false, &async, > fault->write, &fault->map_writable, > @@ -5771,6 +5840,9 @@ int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 err > return -EIO; > } > > + if (r == RET_PF_USER) > + return 0; > + > if (r < 0) > return r; > if (r != RET_PF_EMULATE) > diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h > index d39af5639ce9..268b517e88cb 100644 > --- a/arch/x86/kvm/mmu/mmu_internal.h > +++ b/arch/x86/kvm/mmu/mmu_internal.h > @@ -203,6 +203,7 @@ struct kvm_page_fault { > > /* Derived from mmu and global state. */ > const bool is_tdp; > + const bool is_private; > const bool nx_huge_page_workaround_enabled; > > /* > @@ -259,6 +260,7 @@ int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); > * RET_PF_RETRY: let CPU fault again on the address. > * RET_PF_EMULATE: mmio page fault, emulate the instruction directly. > * RET_PF_INVALID: the spte is invalid, let the real page fault path update it. > + * RET_PF_USER: need to exit to userspace to handle this fault. > * RET_PF_FIXED: The faulting entry has been fixed. > * RET_PF_SPURIOUS: The faulting entry was already fixed, e.g. by another vCPU. > * > @@ -275,6 +277,7 @@ enum { > RET_PF_RETRY, > RET_PF_EMULATE, > RET_PF_INVALID, > + RET_PF_USER, > RET_PF_FIXED, > RET_PF_SPURIOUS, > }; > diff --git a/arch/x86/kvm/mmu/mmutrace.h b/arch/x86/kvm/mmu/mmutrace.h > index ae86820cef69..2d7555381955 100644 > --- a/arch/x86/kvm/mmu/mmutrace.h > +++ b/arch/x86/kvm/mmu/mmutrace.h > @@ -58,6 +58,7 @@ TRACE_DEFINE_ENUM(RET_PF_CONTINUE); > TRACE_DEFINE_ENUM(RET_PF_RETRY); > TRACE_DEFINE_ENUM(RET_PF_EMULATE); > TRACE_DEFINE_ENUM(RET_PF_INVALID); > +TRACE_DEFINE_ENUM(RET_PF_USER); > TRACE_DEFINE_ENUM(RET_PF_FIXED); > TRACE_DEFINE_ENUM(RET_PF_SPURIOUS); > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index aefe67185637..4cf73a579ee1 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3179,9 +3179,9 @@ static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, return level; } -int kvm_mmu_max_mapping_level(struct kvm *kvm, - const struct kvm_memory_slot *slot, gfn_t gfn, - int max_level) +static int __kvm_mmu_max_mapping_level(struct kvm *kvm, + const struct kvm_memory_slot *slot, + gfn_t gfn, int max_level, bool is_private) { struct kvm_lpage_info *linfo; int host_level; @@ -3193,6 +3193,9 @@ int kvm_mmu_max_mapping_level(struct kvm *kvm, break; } + if (is_private) + return max_level; + if (max_level == PG_LEVEL_4K) return PG_LEVEL_4K; @@ -3200,6 +3203,16 @@ int kvm_mmu_max_mapping_level(struct kvm *kvm, return min(host_level, max_level); } +int kvm_mmu_max_mapping_level(struct kvm *kvm, + const struct kvm_memory_slot *slot, gfn_t gfn, + int max_level) +{ + bool is_private = kvm_slot_can_be_private(slot) && + kvm_mem_is_private(kvm, gfn); + + return __kvm_mmu_max_mapping_level(kvm, slot, gfn, max_level, is_private); +} + void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { struct kvm_memory_slot *slot = fault->slot; @@ -3220,8 +3233,9 @@ void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault * Enforce the iTLB multihit workaround after capturing the requested * level, which will be used to do precise, accurate accounting. */ - fault->req_level = kvm_mmu_max_mapping_level(vcpu->kvm, slot, - fault->gfn, fault->max_level); + fault->req_level = __kvm_mmu_max_mapping_level(vcpu->kvm, slot, + fault->gfn, fault->max_level, + fault->is_private); if (fault->req_level == PG_LEVEL_4K || fault->huge_page_disallowed) return; @@ -4304,6 +4318,55 @@ 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 inline u8 kvm_max_level_for_order(int order) +{ + BUILD_BUG_ON(KVM_MAX_HUGEPAGE_LEVEL > PG_LEVEL_1G); + + MMU_WARN_ON(order != KVM_HPAGE_GFN_SHIFT(PG_LEVEL_1G) && + order != KVM_HPAGE_GFN_SHIFT(PG_LEVEL_2M) && + order != KVM_HPAGE_GFN_SHIFT(PG_LEVEL_4K)); + + if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_1G)) + return PG_LEVEL_1G; + + if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_2M)) + return PG_LEVEL_2M; + + return PG_LEVEL_4K; +} + +static int kvm_do_memory_fault_exit(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) +{ + vcpu->run->exit_reason = KVM_EXIT_MEMORY_FAULT; + if (fault->is_private) + vcpu->run->memory.flags = KVM_MEMORY_EXIT_FLAG_PRIVATE; + else + vcpu->run->memory.flags = 0; + vcpu->run->memory.gpa = fault->gfn << PAGE_SHIFT; + vcpu->run->memory.size = PAGE_SIZE; + return RET_PF_USER; +} + +static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) +{ + int max_order, r; + + if (!kvm_slot_can_be_private(fault->slot)) + return kvm_do_memory_fault_exit(vcpu, fault); + + r = kvm_gmem_get_pfn(vcpu->kvm, fault->slot, fault->gfn, &fault->pfn, + &max_order); + if (r) + return r; + + fault->max_level = min(kvm_max_level_for_order(max_order), + fault->max_level); + fault->map_writable = !(fault->slot->flags & KVM_MEM_READONLY); + return RET_PF_CONTINUE; +} + static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { struct kvm_memory_slot *slot = fault->slot; @@ -4336,6 +4399,12 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault return RET_PF_EMULATE; } + if (fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) + return kvm_do_memory_fault_exit(vcpu, fault); + + if (fault->is_private) + return kvm_faultin_pfn_private(vcpu, fault); + async = false; fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, false, &async, fault->write, &fault->map_writable, @@ -5771,6 +5840,9 @@ int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 err return -EIO; } + if (r == RET_PF_USER) + return 0; + if (r < 0) return r; if (r != RET_PF_EMULATE) diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h index d39af5639ce9..268b517e88cb 100644 --- a/arch/x86/kvm/mmu/mmu_internal.h +++ b/arch/x86/kvm/mmu/mmu_internal.h @@ -203,6 +203,7 @@ struct kvm_page_fault { /* Derived from mmu and global state. */ const bool is_tdp; + const bool is_private; const bool nx_huge_page_workaround_enabled; /* @@ -259,6 +260,7 @@ int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); * RET_PF_RETRY: let CPU fault again on the address. * RET_PF_EMULATE: mmio page fault, emulate the instruction directly. * RET_PF_INVALID: the spte is invalid, let the real page fault path update it. + * RET_PF_USER: need to exit to userspace to handle this fault. * RET_PF_FIXED: The faulting entry has been fixed. * RET_PF_SPURIOUS: The faulting entry was already fixed, e.g. by another vCPU. * @@ -275,6 +277,7 @@ enum { RET_PF_RETRY, RET_PF_EMULATE, RET_PF_INVALID, + RET_PF_USER, RET_PF_FIXED, RET_PF_SPURIOUS, }; diff --git a/arch/x86/kvm/mmu/mmutrace.h b/arch/x86/kvm/mmu/mmutrace.h index ae86820cef69..2d7555381955 100644 --- a/arch/x86/kvm/mmu/mmutrace.h +++ b/arch/x86/kvm/mmu/mmutrace.h @@ -58,6 +58,7 @@ TRACE_DEFINE_ENUM(RET_PF_CONTINUE); TRACE_DEFINE_ENUM(RET_PF_RETRY); TRACE_DEFINE_ENUM(RET_PF_EMULATE); TRACE_DEFINE_ENUM(RET_PF_INVALID); +TRACE_DEFINE_ENUM(RET_PF_USER); TRACE_DEFINE_ENUM(RET_PF_FIXED); TRACE_DEFINE_ENUM(RET_PF_SPURIOUS);