If the protected memory feature enabled, unmap guest memory from kernel's direct mappings.
Migration and KSM is disabled for protected memory as it would require a special treatment. Signed-off-by: Kirill A. Shutemov <[email protected]> --- arch/x86/mm/pat/set_memory.c | 1 + include/linux/kvm_host.h | 3 ++ mm/huge_memory.c | 9 +++++ mm/ksm.c | 3 ++ mm/memory.c | 13 +++++++ mm/rmap.c | 4 ++ virt/kvm/kvm_main.c | 74 ++++++++++++++++++++++++++++++++++++ 7 files changed, 107 insertions(+) diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 6f075766bb94..13988413af40 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -2227,6 +2227,7 @@ void __kernel_map_pages(struct page *page, int numpages, int enable) arch_flush_lazy_mmu_mode(); } +EXPORT_SYMBOL_GPL(__kernel_map_pages); #ifdef CONFIG_HIBERNATION bool kernel_page_present(struct page *page) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index b6944f88033d..e1d7762b615c 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -705,6 +705,9 @@ int kvm_protect_all_memory(struct kvm *kvm); int kvm_protect_memory(struct kvm *kvm, unsigned long gfn, unsigned long npages, bool protect); +void kvm_map_page(struct page *page, int nr_pages); +void kvm_unmap_page(struct page *page, int nr_pages); + int gfn_to_page_many_atomic(struct kvm_memory_slot *slot, gfn_t gfn, struct page **pages, int nr_pages); diff --git a/mm/huge_memory.c b/mm/huge_memory.c index c3562648a4ef..d8a444a401cc 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -33,6 +33,7 @@ #include <linux/oom.h> #include <linux/numa.h> #include <linux/page_owner.h> +#include <linux/kvm_host.h> #include <asm/tlb.h> #include <asm/pgalloc.h> @@ -650,6 +651,10 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, spin_unlock(vmf->ptl); count_vm_event(THP_FAULT_ALLOC); count_memcg_events(memcg, THP_FAULT_ALLOC, 1); + + /* Unmap page from direct mapping */ + if (vma_is_kvm_protected(vma)) + kvm_unmap_page(page, HPAGE_PMD_NR); } return 0; @@ -1886,6 +1891,10 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, page_remove_rmap(page, true); VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); VM_BUG_ON_PAGE(!PageHead(page), page); + + /* Map the page back to the direct mapping */ + if (vma_is_kvm_protected(vma)) + kvm_map_page(page, HPAGE_PMD_NR); } else if (thp_migration_supported()) { swp_entry_t entry; diff --git a/mm/ksm.c b/mm/ksm.c index 281c00129a2e..942b88782ac2 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -527,6 +527,9 @@ static struct vm_area_struct *find_mergeable_vma(struct mm_struct *mm, return NULL; if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma) return NULL; + /* TODO */ + if (vma_is_kvm_protected(vma)) + return NULL; return vma; } diff --git a/mm/memory.c b/mm/memory.c index d7228db6e4bf..74773229b854 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -71,6 +71,7 @@ #include <linux/dax.h> #include <linux/oom.h> #include <linux/numa.h> +#include <linux/kvm_host.h> #include <trace/events/kmem.h> @@ -1088,6 +1089,11 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, likely(!(vma->vm_flags & VM_SEQ_READ))) mark_page_accessed(page); } + + /* Map the page back to the direct mapping */ + if (vma_is_anonymous(vma) && vma_is_kvm_protected(vma)) + kvm_map_page(page, 1); + rss[mm_counter(page)]--; page_remove_rmap(page, false); if (unlikely(page_mapcount(page) < 0)) @@ -3312,6 +3318,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf) struct page *page; vm_fault_t ret = 0; pte_t entry; + bool set = false; /* File mapping without ->vm_ops ? */ if (vma->vm_flags & VM_SHARED) @@ -3397,6 +3404,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf) page_add_new_anon_rmap(page, vma, vmf->address, false); mem_cgroup_commit_charge(page, memcg, false, false); lru_cache_add_active_or_unevictable(page, vma); + set = true; setpte: set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry); @@ -3404,6 +3412,11 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf) update_mmu_cache(vma, vmf->address, vmf->pte); unlock: pte_unmap_unlock(vmf->pte, vmf->ptl); + + /* Unmap page from direct mapping */ + if (vma_is_kvm_protected(vma) && set) + kvm_unmap_page(page, 1); + return ret; release: mem_cgroup_cancel_charge(page, memcg, false); diff --git a/mm/rmap.c b/mm/rmap.c index f79a206b271a..a9b2e347d1ab 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1709,6 +1709,10 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg) { + /* TODO */ + if (vma_is_kvm_protected(vma)) + return true; + return vma_is_temporary_stack(vma); } diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 71aac117357f..defc33d3a124 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -51,6 +51,7 @@ #include <linux/io.h> #include <linux/lockdep.h> #include <linux/kthread.h> +#include <linux/pagewalk.h> #include <asm/processor.h> #include <asm/ioctl.h> @@ -2718,6 +2719,72 @@ void kvm_vcpu_mark_page_dirty(struct kvm_vcpu *vcpu, gfn_t gfn) } EXPORT_SYMBOL_GPL(kvm_vcpu_mark_page_dirty); +void kvm_map_page(struct page *page, int nr_pages) +{ + int i; + + /* Clear page before returning it to the direct mapping */ + for (i = 0; i < nr_pages; i++) { + void *p = map_page_atomic(page + i); + memset(p, 0, PAGE_SIZE); + unmap_page_atomic(p); + } + + kernel_map_pages(page, nr_pages, 1); +} +EXPORT_SYMBOL_GPL(kvm_map_page); + +void kvm_unmap_page(struct page *page, int nr_pages) +{ + kernel_map_pages(page, nr_pages, 0); +} +EXPORT_SYMBOL_GPL(kvm_unmap_page); + +static int adjust_direct_mapping_pte_range(pmd_t *pmd, unsigned long addr, + unsigned long end, + struct mm_walk *walk) +{ + bool protect = (bool)walk->private; + pte_t *pte; + struct page *page; + + if (pmd_trans_huge(*pmd)) { + page = pmd_page(*pmd); + if (is_huge_zero_page(page)) + return 0; + VM_BUG_ON_PAGE(total_mapcount(page) != 1, page); + /* XXX: Would it fail with direct device assignment? */ + VM_BUG_ON_PAGE(page_count(page) != 1, page); + kernel_map_pages(page, HPAGE_PMD_NR, !protect); + return 0; + } + + pte = pte_offset_map(pmd, addr); + for (; addr != end; pte++, addr += PAGE_SIZE) { + pte_t entry = *pte; + + if (!pte_present(entry)) + continue; + + if (is_zero_pfn(pte_pfn(entry))) + continue; + + page = pte_page(entry); + + VM_BUG_ON_PAGE(page_mapcount(page) != 1, page); + /* XXX: Would it fail with direct device assignment? */ + VM_BUG_ON_PAGE(page_count(page) != + total_mapcount(compound_head(page)), page); + kernel_map_pages(page, 1, !protect); + } + + return 0; +} + +static const struct mm_walk_ops adjust_direct_mapping_ops = { + .pmd_entry = adjust_direct_mapping_pte_range, +}; + static int protect_memory(unsigned long start, unsigned long end, bool protect) { struct mm_struct *mm = current->mm; @@ -2763,6 +2830,13 @@ static int protect_memory(unsigned long start, unsigned long end, bool protect) if (ret) goto out; + if (vma_is_anonymous(vma)) { + ret = walk_page_range_novma(mm, start, tmp, + &adjust_direct_mapping_ops, NULL, + (void *) protect); + if (ret) + goto out; + } next: start = tmp; if (start < prev->vm_end) -- 2.26.2
