Merge tag 'kvm-arm-fixes-4.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm

Fixes for KVM/ARM for 4.0-rc5.

Fixes page refcounting issues in our Stage-2 page table management code,
fixes a missing unlock in a gicv3 error path, and fixes a race that can
cause lost interrupts if signals are pending just prior to entering the
guest.

2 files changed, 59 insertions, 29 deletions

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index bf0fe99e8ca9..4cf48c3aca13 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -149,29 +149,28 @@ static inline bool kvm_s2pmd_readonly(pmd_t *pmd)
         (__boundary - 1 < (end) - 1)? __boundary: (end);                \
 })
 
+#define kvm_pgd_index(addr)                     pgd_index(addr)
+
 static inline bool kvm_page_empty(void *ptr)
 {
         struct page *ptr_page = virt_to_page(ptr);
         return page_count(ptr_page) == 1;
 }
 
-
 #define kvm_pte_table_empty(kvm, ptep) kvm_page_empty(ptep)
 #define kvm_pmd_table_empty(kvm, pmdp) kvm_page_empty(pmdp)
 #define kvm_pud_table_empty(kvm, pudp) (0)
 
 #define KVM_PREALLOC_LEVEL      0
 
-static inline int kvm_prealloc_hwpgd(struct kvm *kvm, pgd_t *pgd)
+static inline void *kvm_get_hwpgd(struct kvm *kvm)
 {
-        return 0;
+        return kvm->arch.pgd;
 }
 
-static inline void kvm_free_hwpgd(struct kvm *kvm) { }
-
-static inline void *kvm_get_hwpgd(struct kvm *kvm)
+static inline unsigned int kvm_get_hwpgd_size(void)
 {
-        return kvm->arch.pgd;
+        return PTRS_PER_S2_PGD * sizeof(pgd_t);
 }
 
 struct kvm;
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 3e6859bc3e11..5656d79c5a44 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -290,7 +290,7 @@ static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
         phys_addr_t addr = start, end = start + size;
         phys_addr_t next;
 
-        pgd = pgdp + pgd_index(addr);
+        pgd = pgdp + kvm_pgd_index(addr);
         do {
                 next = kvm_pgd_addr_end(addr, end);
                 if (!pgd_none(*pgd))
@@ -355,7 +355,7 @@ static void stage2_flush_memslot(struct kvm *kvm,
         phys_addr_t next;
         pgd_t *pgd;
 
-        pgd = kvm->arch.pgd + pgd_index(addr);
+        pgd = kvm->arch.pgd + kvm_pgd_index(addr);
         do {
                 next = kvm_pgd_addr_end(addr, end);
                 stage2_flush_puds(kvm, pgd, addr, next);
@@ -632,6 +632,20 @@ int create_hyp_io_mappings(void *from, void *to, phys_addr_t phys_addr)
                                      __phys_to_pfn(phys_addr), PAGE_HYP_DEVICE);
 }
 
+/* Free the HW pgd, one page at a time */
+static void kvm_free_hwpgd(void *hwpgd)
+{
+        free_pages_exact(hwpgd, kvm_get_hwpgd_size());
+}
+
+/* Allocate the HW PGD, making sure that each page gets its own refcount */
+static void *kvm_alloc_hwpgd(void)
+{
+        unsigned int size = kvm_get_hwpgd_size();
+
+        return alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
+}
+
 /**
  * kvm_alloc_stage2_pgd - allocate level-1 table for stage-2 translation.
  * @kvm:        The KVM struct pointer for the VM.
@@ -645,15 +659,31 @@ int create_hyp_io_mappings(void *from, void *to, phys_addr_t phys_addr)
  */
 int kvm_alloc_stage2_pgd(struct kvm *kvm)
 {
-        int ret;
         pgd_t *pgd;
+        void *hwpgd;
 
         if (kvm->arch.pgd != NULL) {
                 kvm_err("kvm_arch already initialized?\n");
                 return -EINVAL;
         }
 
+        hwpgd = kvm_alloc_hwpgd();
+        if (!hwpgd)
+                return -ENOMEM;
+
+        /* When the kernel uses more levels of page tables than the
+         * guest, we allocate a fake PGD and pre-populate it to point
+         * to the next-level page table, which will be the real
+         * initial page table pointed to by the VTTBR.
+         *
+         * When KVM_PREALLOC_LEVEL==2, we allocate a single page for
+         * the PMD and the kernel will use folded pud.
+         * When KVM_PREALLOC_LEVEL==1, we allocate 2 consecutive PUD
+         * pages.
+         */
         if (KVM_PREALLOC_LEVEL > 0) {
+                int i;
+
                 /*
                  * Allocate fake pgd for the page table manipulation macros to
                  * work.  This is not used by the hardware and we have no
@@ -661,30 +691,32 @@ int kvm_alloc_stage2_pgd(struct kvm *kvm)
                  */
                 pgd = (pgd_t *)kmalloc(PTRS_PER_S2_PGD * sizeof(pgd_t),
                                        GFP_KERNEL | __GFP_ZERO);
+
+                if (!pgd) {
+                        kvm_free_hwpgd(hwpgd);
+                        return -ENOMEM;
+                }
+
+                /* Plug the HW PGD into the fake one. */
+                for (i = 0; i < PTRS_PER_S2_PGD; i++) {
+                        if (KVM_PREALLOC_LEVEL == 1)
+                                pgd_populate(NULL, pgd + i,
+                                             (pud_t *)hwpgd + i * PTRS_PER_PUD);
+                        else if (KVM_PREALLOC_LEVEL == 2)
+                                pud_populate(NULL, pud_offset(pgd, 0) + i,
+                                             (pmd_t *)hwpgd + i * PTRS_PER_PMD);
+                }
         } else {
                 /*
                  * Allocate actual first-level Stage-2 page table used by the
                  * hardware for Stage-2 page table walks.
                  */
-                pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, S2_PGD_ORDER);
+                pgd = (pgd_t *)hwpgd;
         }
 
-        if (!pgd)
-                return -ENOMEM;
-
-        ret = kvm_prealloc_hwpgd(kvm, pgd);
-        if (ret)
-                goto out_err;
-
         kvm_clean_pgd(pgd);
         kvm->arch.pgd = pgd;
         return 0;
-out_err:
-        if (KVM_PREALLOC_LEVEL > 0)
-                kfree(pgd);
-        else
-                free_pages((unsigned long)pgd, S2_PGD_ORDER);
-        return ret;
 }
 
 /**
@@ -785,11 +817,10 @@ void kvm_free_stage2_pgd(struct kvm *kvm)
                 return;
 
         unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE);
-        kvm_free_hwpgd(kvm);
+        kvm_free_hwpgd(kvm_get_hwpgd(kvm));
         if (KVM_PREALLOC_LEVEL > 0)
                 kfree(kvm->arch.pgd);
-        else
-                free_pages((unsigned long)kvm->arch.pgd, S2_PGD_ORDER);
+
         kvm->arch.pgd = NULL;
 }
 
@@ -799,7 +830,7 @@ static pud_t *stage2_get_pud(struct kvm *kvm, struct kvm_mmu_memory_cache *cache
         pgd_t *pgd;
         pud_t *pud;
 
-        pgd = kvm->arch.pgd + pgd_index(addr);
+        pgd = kvm->arch.pgd + kvm_pgd_index(addr);
         if (WARN_ON(pgd_none(*pgd))) {
                 if (!cache)
                         return NULL;
@@ -1089,7 +1120,7 @@ static void stage2_wp_range(struct kvm *kvm, phys_addr_t addr, phys_addr_t end)
         pgd_t *pgd;
         phys_addr_t next;
 
-        pgd = kvm->arch.pgd + pgd_index(addr);
+        pgd = kvm->arch.pgd + kvm_pgd_index(addr);
         do {
                 /*
                  * Release kvm_mmu_lock periodically if the memory region is