KVM: Move gfn_to_page out of kmap/unmap pairs

gfn_to_page might sleep with swap support. Move it out of the kmap calls.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 47 insertions, 33 deletions

diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index 01901ec3fe80..660243b39d84 100644
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -58,7 +58,10 @@ struct guest_walker {
         int level;
         gfn_t table_gfn[PT_MAX_FULL_LEVELS];
         pt_element_t *table;
+        pt_element_t pte;
         pt_element_t *ptep;
+        struct page *page;
+        int index;
         pt_element_t inherited_ar;
         gfn_t gfn;
         u32 error_code;
@@ -80,11 +83,14 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
         pgprintk("%s: addr %lx\n", __FUNCTION__, addr);
         walker->level = vcpu->mmu.root_level;
         walker->table = NULL;
+        walker->page = NULL;
+        walker->ptep = NULL;
         root = vcpu->cr3;
 #if PTTYPE == 64
         if (!is_long_mode(vcpu)) {
                 walker->ptep = &vcpu->pdptrs[(addr >> 30) & 3];
                 root = *walker->ptep;
+                walker->pte = root;
                 if (!(root & PT_PRESENT_MASK))
                         goto not_present;
                 --walker->level;
@@ -96,7 +102,8 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
                  walker->level - 1, table_gfn);
         slot = gfn_to_memslot(vcpu->kvm, table_gfn);
         hpa = safe_gpa_to_hpa(vcpu, root & PT64_BASE_ADDR_MASK);
-        walker->table = kmap_atomic(pfn_to_page(hpa >> PAGE_SHIFT), KM_USER0);
+        walker->page = pfn_to_page(hpa >> PAGE_SHIFT);
+        walker->table = kmap_atomic(walker->page, KM_USER0);
 
         ASSERT((!is_long_mode(vcpu) && is_pae(vcpu)) ||
                (vcpu->cr3 & CR3_NONPAE_RESERVED_BITS) == 0);
@@ -108,6 +115,7 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
                 hpa_t paddr;
 
                 ptep = &walker->table[index];
+                walker->index = index;
                 ASSERT(((unsigned long)walker->table & PAGE_MASK) ==
                        ((unsigned long)ptep & PAGE_MASK));
 
@@ -148,16 +156,20 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
 
                 walker->inherited_ar &= walker->table[index];
                 table_gfn = (*ptep & PT_BASE_ADDR_MASK) >> PAGE_SHIFT;
-                paddr = safe_gpa_to_hpa(vcpu, *ptep & PT_BASE_ADDR_MASK);
                 kunmap_atomic(walker->table, KM_USER0);
-                walker->table = kmap_atomic(pfn_to_page(paddr >> PAGE_SHIFT),
-                                            KM_USER0);
+                paddr = safe_gpa_to_hpa(vcpu, table_gfn << PAGE_SHIFT);
+                walker->page = pfn_to_page(paddr >> PAGE_SHIFT);
+                walker->table = kmap_atomic(walker->page, KM_USER0);
                 --walker->level;
                 walker->table_gfn[walker->level - 1 ] = table_gfn;
                 pgprintk("%s: table_gfn[%d] %lx\n", __FUNCTION__,
                          walker->level - 1, table_gfn);
         }
-        walker->ptep = ptep;
+        walker->pte = *ptep;
+        if (walker->page)
+                walker->ptep = NULL;
+        if (walker->table)
+                kunmap_atomic(walker->table, KM_USER0);
         pgprintk("%s: pte %llx\n", __FUNCTION__, (u64)*ptep);
         return 1;
 
@@ -175,13 +187,9 @@ err:
                 walker->error_code |= PFERR_USER_MASK;
         if (fetch_fault)
                 walker->error_code |= PFERR_FETCH_MASK;
-        return 0;
-}
-
-static void FNAME(release_walker)(struct guest_walker *walker)
-{
         if (walker->table)
                 kunmap_atomic(walker->table, KM_USER0);
+        return 0;
 }
 
 static void FNAME(mark_pagetable_dirty)(struct kvm *kvm,
@@ -193,7 +201,7 @@ static void FNAME(mark_pagetable_dirty)(struct kvm *kvm,
 static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu,
                                   u64 *shadow_pte,
                                   gpa_t gaddr,
-                                  pt_element_t *gpte,
+                                  pt_element_t gpte,
                                   u64 access_bits,
                                   int user_fault,
                                   int write_fault,
@@ -202,23 +210,34 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu,
                                   gfn_t gfn)
 {
         hpa_t paddr;
-        int dirty = *gpte & PT_DIRTY_MASK;
+        int dirty = gpte & PT_DIRTY_MASK;
         u64 spte = *shadow_pte;
         int was_rmapped = is_rmap_pte(spte);
 
         pgprintk("%s: spte %llx gpte %llx access %llx write_fault %d"
                  " user_fault %d gfn %lx\n",
-                 __FUNCTION__, spte, (u64)*gpte, access_bits,
+                 __FUNCTION__, spte, (u64)gpte, access_bits,
                  write_fault, user_fault, gfn);
 
         if (write_fault && !dirty) {
-                *gpte |= PT_DIRTY_MASK;
+                pt_element_t *guest_ent, *tmp = NULL;
+
+                if (walker->ptep)
+                        guest_ent = walker->ptep;
+                else {
+                        tmp = kmap_atomic(walker->page, KM_USER0);
+                        guest_ent = &tmp[walker->index];
+                }
+
+                *guest_ent |= PT_DIRTY_MASK;
+                if (!walker->ptep)
+                        kunmap_atomic(tmp, KM_USER0);
                 dirty = 1;
                 FNAME(mark_pagetable_dirty)(vcpu->kvm, walker);
         }
 
         spte |= PT_PRESENT_MASK | PT_ACCESSED_MASK | PT_DIRTY_MASK;
-        spte |= *gpte & PT64_NX_MASK;
+        spte |= gpte & PT64_NX_MASK;
         if (!dirty)
                 access_bits &= ~PT_WRITABLE_MASK;
 
@@ -273,13 +292,13 @@ unshadowed:
                 rmap_add(vcpu, shadow_pte);
 }
 
-static void FNAME(set_pte)(struct kvm_vcpu *vcpu, pt_element_t *gpte,
+static void FNAME(set_pte)(struct kvm_vcpu *vcpu, pt_element_t gpte,
                            u64 *shadow_pte, u64 access_bits,
                            int user_fault, int write_fault, int *ptwrite,
                            struct guest_walker *walker, gfn_t gfn)
 {
-        access_bits &= *gpte;
-        FNAME(set_pte_common)(vcpu, shadow_pte, *gpte & PT_BASE_ADDR_MASK,
+        access_bits &= gpte;
+        FNAME(set_pte_common)(vcpu, shadow_pte, gpte & PT_BASE_ADDR_MASK,
                               gpte, access_bits, user_fault, write_fault,
                               ptwrite, walker, gfn);
 }
@@ -295,22 +314,22 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
         if (~gpte & (PT_PRESENT_MASK | PT_ACCESSED_MASK))
                 return;
         pgprintk("%s: gpte %llx spte %p\n", __FUNCTION__, (u64)gpte, spte);
-        FNAME(set_pte)(vcpu, &gpte, spte, PT_USER_MASK | PT_WRITABLE_MASK, 0,
+        FNAME(set_pte)(vcpu, gpte, spte, PT_USER_MASK | PT_WRITABLE_MASK, 0,
                        0, NULL, NULL,
                        (gpte & PT_BASE_ADDR_MASK) >> PAGE_SHIFT);
 }
 
-static void FNAME(set_pde)(struct kvm_vcpu *vcpu, pt_element_t *gpde,
+static void FNAME(set_pde)(struct kvm_vcpu *vcpu, pt_element_t gpde,
                            u64 *shadow_pte, u64 access_bits,
                            int user_fault, int write_fault, int *ptwrite,
                            struct guest_walker *walker, gfn_t gfn)
 {
         gpa_t gaddr;
 
-        access_bits &= *gpde;
+        access_bits &= gpde;
         gaddr = (gpa_t)gfn << PAGE_SHIFT;
         if (PTTYPE == 32 && is_cpuid_PSE36())
-                gaddr |= (*gpde & PT32_DIR_PSE36_MASK) <<
+                gaddr |= (gpde & PT32_DIR_PSE36_MASK) <<
                         (32 - PT32_DIR_PSE36_SHIFT);
         FNAME(set_pte_common)(vcpu, shadow_pte, gaddr,
                               gpde, access_bits, user_fault, write_fault,
@@ -328,9 +347,8 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
         int level;
         u64 *shadow_ent;
         u64 *prev_shadow_ent = NULL;
-        pt_element_t *guest_ent = walker->ptep;
 
-        if (!is_present_pte(*guest_ent))
+        if (!is_present_pte(walker->pte))
                 return NULL;
 
         shadow_addr = vcpu->mmu.root_hpa;
@@ -364,12 +382,12 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
                 if (level - 1 == PT_PAGE_TABLE_LEVEL
                     && walker->level == PT_DIRECTORY_LEVEL) {
                         metaphysical = 1;
-                        hugepage_access = *guest_ent;
+                        hugepage_access = walker->pte;
                         hugepage_access &= PT_USER_MASK | PT_WRITABLE_MASK;
-                        if (*guest_ent & PT64_NX_MASK)
+                        if (walker->pte & PT64_NX_MASK)
                                 hugepage_access |= (1 << 2);
                         hugepage_access >>= PT_WRITABLE_SHIFT;
-                        table_gfn = (*guest_ent & PT_BASE_ADDR_MASK)
+                        table_gfn = (walker->pte & PT_BASE_ADDR_MASK)
                                 >> PAGE_SHIFT;
                 } else {
                         metaphysical = 0;
@@ -386,12 +404,12 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
         }
 
         if (walker->level == PT_DIRECTORY_LEVEL) {
-                FNAME(set_pde)(vcpu, guest_ent, shadow_ent,
+                FNAME(set_pde)(vcpu, walker->pte, shadow_ent,
                                walker->inherited_ar, user_fault, write_fault,
                                ptwrite, walker, walker->gfn);
         } else {
                 ASSERT(walker->level == PT_PAGE_TABLE_LEVEL);
-                FNAME(set_pte)(vcpu, guest_ent, shadow_ent,
+                FNAME(set_pte)(vcpu, walker->pte, shadow_ent,
                                walker->inherited_ar, user_fault, write_fault,
                                ptwrite, walker, walker->gfn);
         }
@@ -442,7 +460,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
         if (!r) {
                 pgprintk("%s: guest page fault\n", __FUNCTION__);
                 inject_page_fault(vcpu, addr, walker.error_code);
-                FNAME(release_walker)(&walker);
                 vcpu->last_pt_write_count = 0; /* reset fork detector */
                 return 0;
         }
@@ -452,8 +469,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
         pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __FUNCTION__,
                  shadow_pte, *shadow_pte, write_pt);
 
-        FNAME(release_walker)(&walker);
-
         if (!write_pt)
                 vcpu->last_pt_write_count = 0; /* reset fork detector */
 
@@ -482,7 +497,6 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)
                 gpa |= vaddr & ~PAGE_MASK;
         }
 
-        FNAME(release_walker)(&walker);
         return gpa;
 }