Introduce helper functions to map and unmap guest memory into host kernel memory. These helper functions support mapping guest memory both that are managed by the host kernel (i.e. have a "struct page") and the ones that are not managed by the kernel (i.e. does not have a "struct page").
Cc: Paolo Bonzini <[email protected]> Cc: Radim Krčmář <[email protected]> Cc: [email protected] Cc: [email protected] Signed-off-by: KarimAllah Ahmed <[email protected]> --- include/linux/kvm_host.h | 18 ++++++++++++++ virt/kvm/kvm_main.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 80 insertions(+) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 6bdd4b9..45d2854 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -204,6 +204,12 @@ enum { READING_SHADOW_PAGE_TABLES, }; +struct kvm_host_mapping { + struct page *page; + void *kaddr; + kvm_pfn_t pfn; +}; + /* * Sometimes a large or cross-page mmio needs to be broken up into separate * exits for userspace servicing. @@ -700,6 +706,10 @@ struct kvm_memslots *kvm_vcpu_memslots(struct kvm_vcpu *vcpu); struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn); kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn); kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn); +bool kvm_vcpu_gfn_to_host_mapping(struct kvm_vcpu *vcpu, gfn_t gfn, + struct kvm_host_mapping *mapping, + bool kernel_access); +void kvm_release_host_mapping(struct kvm_host_mapping *mapping, bool dirty); struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn); unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn); unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *writable); @@ -990,6 +1000,14 @@ static inline hpa_t pfn_to_hpa(kvm_pfn_t pfn) return (hpa_t)pfn << PAGE_SHIFT; } +static inline bool kvm_vcpu_gpa_to_host_mapping(struct kvm_vcpu *vcpu, gpa_t gpa, + struct kvm_host_mapping *mapping, + bool kernel_access) +{ + return kvm_vcpu_gfn_to_host_mapping(vcpu, gpa_to_gfn(gpa), mapping, + kernel_access); +} + static inline struct page *kvm_vcpu_gpa_to_page(struct kvm_vcpu *vcpu, gpa_t gpa) { diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 210bf82..2b9f93d 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1653,6 +1653,68 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn) } EXPORT_SYMBOL_GPL(gfn_to_page); +bool kvm_vcpu_gfn_to_host_mapping(struct kvm_vcpu *vcpu, gfn_t gfn, + struct kvm_host_mapping *mapping, + bool kernel_access) +{ + void *kaddr = NULL; + kvm_pfn_t pfn; + struct page *page = NULL; + + pfn = kvm_vcpu_gfn_to_pfn(vcpu, gfn); + + if (pfn_valid(pfn)) { + page = kvm_pfn_to_page(pfn); + if (is_error_page(page)) + return false; + + if (kernel_access) { + kaddr = kmap(page); + if (!kaddr) + return false; + } + + mapping->kaddr = kaddr; + mapping->page = page; + mapping->pfn = pfn; + return true; + } + + kaddr = memremap(pfn << PAGE_SHIFT, PAGE_SIZE, MEMREMAP_WB); + if (!kaddr) + return false; + + mapping->page = NULL; + mapping->kaddr = kaddr; + mapping->pfn = pfn; + + return true; +} +EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_kaddr); + +void kvm_release_host_mapping(struct kvm_host_mapping *mapping, bool dirty) +{ + if (mapping->page) { + if (mapping->kaddr) + kunmap(mapping->page); + + if (dirty) + kvm_release_page_dirty(mapping->page); + else + kvm_release_page_clean(mapping->page); + } else { + if (mapping->kaddr) + memunmap(mapping->kaddr); + + if (dirty) + kvm_release_pfn_dirty(mapping->pfn); + else + kvm_release_pfn_clean(mapping->pfn); + } + + memset(mapping, 0, sizeof(*mapping)); +} + struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn) { kvm_pfn_t pfn; -- 2.7.4
