[PATCH v4 5/7] ARM: KVM: rework HYP page table freeing
Marc Zyngier
marc.zyngier at arm.com
Fri Apr 12 14:12:05 EDT 2013
There is no point in freeing HYP page tables differently from Stage-2.
They now have the same requirements, and should be dealt with the same way.
Promote unmap_stage2_range to be The One True Way, and get rid of a number
of nasty bugs in the process (goo thing we never actually called free_hyp_pmds
before...).
Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
arch/arm/include/asm/kvm_mmu.h | 2 +-
arch/arm/kvm/arm.c | 2 +-
arch/arm/kvm/mmu.c | 181 ++++++++++++++++++-----------------------
3 files changed, 82 insertions(+), 103 deletions(-)
diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 3c71a1d..92eb20d 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -32,7 +32,7 @@
int create_hyp_mappings(void *from, void *to);
int create_hyp_io_mappings(void *from, void *to, phys_addr_t);
-void free_hyp_pmds(void);
+void free_hyp_pgds(void);
int kvm_alloc_stage2_pgd(struct kvm *kvm);
void kvm_free_stage2_pgd(struct kvm *kvm);
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 23538ed..8992f05 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -937,7 +937,7 @@ static int init_hyp_mode(void)
out_free_context:
free_percpu(kvm_host_cpu_state);
out_free_mappings:
- free_hyp_pmds();
+ free_hyp_pgds();
out_free_stack_pages:
for_each_possible_cpu(cpu)
free_page(per_cpu(kvm_arm_hyp_stack_page, cpu));
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index bfc5927..7464824 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -72,56 +72,104 @@ static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
return p;
}
-static void free_ptes(pmd_t *pmd, unsigned long addr)
+static void clear_pud_entry(pud_t *pud)
{
- pte_t *pte;
- unsigned int i;
+ pmd_t *pmd_table = pmd_offset(pud, 0);
+ pud_clear(pud);
+ pmd_free(NULL, pmd_table);
+ put_page(virt_to_page(pud));
+}
- for (i = 0; i < PTRS_PER_PMD; i++, addr += PMD_SIZE) {
- if (!pmd_none(*pmd) && pmd_table(*pmd)) {
- pte = pte_offset_kernel(pmd, addr);
- pte_free_kernel(NULL, pte);
- }
- pmd++;
+static void clear_pmd_entry(pmd_t *pmd)
+{
+ pte_t *pte_table = pte_offset_kernel(pmd, 0);
+ pmd_clear(pmd);
+ pte_free_kernel(NULL, pte_table);
+ put_page(virt_to_page(pmd));
+}
+
+static bool pmd_empty(pmd_t *pmd)
+{
+ struct page *pmd_page = virt_to_page(pmd);
+ return page_count(pmd_page) == 1;
+}
+
+static void clear_pte_entry(pte_t *pte)
+{
+ if (pte_present(*pte)) {
+ kvm_set_pte(pte, __pte(0));
+ put_page(virt_to_page(pte));
}
}
-static void free_hyp_pgd_entry(unsigned long addr)
+static bool pte_empty(pte_t *pte)
+{
+ struct page *pte_page = virt_to_page(pte);
+ return page_count(pte_page) == 1;
+}
+
+static void unmap_range(pgd_t *pgdp, unsigned long long start, u64 size)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
- unsigned long hyp_addr = KERN_TO_HYP(addr);
+ pte_t *pte;
+ unsigned long long addr = start, end = start + size;
+ u64 range;
- pgd = hyp_pgd + pgd_index(hyp_addr);
- pud = pud_offset(pgd, hyp_addr);
+ while (addr < end) {
+ pgd = pgdp + pgd_index(addr);
+ pud = pud_offset(pgd, addr);
+ if (pud_none(*pud)) {
+ addr += PUD_SIZE;
+ continue;
+ }
- if (pud_none(*pud))
- return;
- BUG_ON(pud_bad(*pud));
+ pmd = pmd_offset(pud, addr);
+ if (pmd_none(*pmd)) {
+ addr += PMD_SIZE;
+ continue;
+ }
- pmd = pmd_offset(pud, hyp_addr);
- free_ptes(pmd, addr);
- pmd_free(NULL, pmd);
- pud_clear(pud);
+ pte = pte_offset_kernel(pmd, addr);
+ clear_pte_entry(pte);
+ range = PAGE_SIZE;
+
+ /* If we emptied the pte, walk back up the ladder */
+ if (pte_empty(pte)) {
+ clear_pmd_entry(pmd);
+ range = PMD_SIZE;
+ if (pmd_empty(pmd)) {
+ clear_pud_entry(pud);
+ range = PUD_SIZE;
+ }
+ }
+
+ addr += range;
+ }
}
/**
- * free_hyp_pmds - free a Hyp-mode level-2 tables and child level-3 tables
+ * free_hyp_pgds - free Hyp-mode page tables
*
- * Assumes this is a page table used strictly in Hyp-mode and therefore contains
+ * Assumes hyp_pgd is a page table used strictly in Hyp-mode and therefore contains
* either mappings in the kernel memory area (above PAGE_OFFSET), or
* device mappings in the vmalloc range (from VMALLOC_START to VMALLOC_END).
*/
-void free_hyp_pmds(void)
+void free_hyp_pgds(void)
{
unsigned long addr;
mutex_lock(&kvm_hyp_pgd_mutex);
- for (addr = PAGE_OFFSET; virt_addr_valid(addr); addr += PGDIR_SIZE)
- free_hyp_pgd_entry(addr);
- for (addr = VMALLOC_START; is_vmalloc_addr((void*)addr); addr += PGDIR_SIZE)
- free_hyp_pgd_entry(addr);
+
+ if (hyp_pgd) {
+ for (addr = PAGE_OFFSET; virt_addr_valid(addr); addr += PGDIR_SIZE)
+ unmap_range(hyp_pgd, KERN_TO_HYP(addr), PGDIR_SIZE);
+ for (addr = VMALLOC_START; is_vmalloc_addr((void*)addr); addr += PGDIR_SIZE)
+ unmap_range(hyp_pgd, KERN_TO_HYP(addr), PGDIR_SIZE);
+ kfree(hyp_pgd);
+ }
+
mutex_unlock(&kvm_hyp_pgd_mutex);
}
@@ -136,6 +184,7 @@ static void create_hyp_pte_mappings(pmd_t *pmd, unsigned long start,
do {
pte = pte_offset_kernel(pmd, addr);
kvm_set_pte(pte, pfn_pte(pfn, prot));
+ get_page(virt_to_page(pte));
pfn++;
} while (addr += PAGE_SIZE, addr != end);
}
@@ -161,6 +210,7 @@ static int create_hyp_pmd_mappings(pud_t *pud, unsigned long start,
return -ENOMEM;
}
pmd_populate_kernel(NULL, pmd, pte);
+ get_page(virt_to_page(pmd));
}
next = pmd_addr_end(addr, end);
@@ -197,6 +247,7 @@ static int __create_hyp_mappings(pgd_t *pgdp,
goto out;
}
pud_populate(NULL, pud, pmd);
+ get_page(virt_to_page(pud));
}
next = pgd_addr_end(addr, end);
@@ -289,42 +340,6 @@ int kvm_alloc_stage2_pgd(struct kvm *kvm)
return 0;
}
-static void clear_pud_entry(pud_t *pud)
-{
- pmd_t *pmd_table = pmd_offset(pud, 0);
- pud_clear(pud);
- pmd_free(NULL, pmd_table);
- put_page(virt_to_page(pud));
-}
-
-static void clear_pmd_entry(pmd_t *pmd)
-{
- pte_t *pte_table = pte_offset_kernel(pmd, 0);
- pmd_clear(pmd);
- pte_free_kernel(NULL, pte_table);
- put_page(virt_to_page(pmd));
-}
-
-static bool pmd_empty(pmd_t *pmd)
-{
- struct page *pmd_page = virt_to_page(pmd);
- return page_count(pmd_page) == 1;
-}
-
-static void clear_pte_entry(pte_t *pte)
-{
- if (pte_present(*pte)) {
- kvm_set_pte(pte, __pte(0));
- put_page(virt_to_page(pte));
- }
-}
-
-static bool pte_empty(pte_t *pte)
-{
- struct page *pte_page = virt_to_page(pte);
- return page_count(pte_page) == 1;
-}
-
/**
* unmap_stage2_range -- Clear stage2 page table entries to unmap a range
* @kvm: The VM pointer
@@ -338,43 +353,7 @@ static bool pte_empty(pte_t *pte)
*/
static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size)
{
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *pte;
- phys_addr_t addr = start, end = start + size;
- u64 range;
-
- while (addr < end) {
- pgd = kvm->arch.pgd + pgd_index(addr);
- pud = pud_offset(pgd, addr);
- if (pud_none(*pud)) {
- addr += PUD_SIZE;
- continue;
- }
-
- pmd = pmd_offset(pud, addr);
- if (pmd_none(*pmd)) {
- addr += PMD_SIZE;
- continue;
- }
-
- pte = pte_offset_kernel(pmd, addr);
- clear_pte_entry(pte);
- range = PAGE_SIZE;
-
- /* If we emptied the pte, walk back up the ladder */
- if (pte_empty(pte)) {
- clear_pmd_entry(pmd);
- range = PMD_SIZE;
- if (pmd_empty(pmd)) {
- clear_pud_entry(pud);
- range = PUD_SIZE;
- }
- }
-
- addr += range;
- }
+ unmap_range(kvm->arch.pgd, start, size);
}
/**
@@ -741,7 +720,7 @@ int kvm_mmu_init(void)
return 0;
out:
- kfree(hyp_pgd);
+ free_hyp_pgds();
return err;
}
--
1.8.1.4
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