diff mbox

[v2,1/5] ARM: KVM: be more thorough when invalidating TLBs

Message ID 1367505542-2231-2-git-send-email-marc.zyngier@arm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Marc Zyngier May 2, 2013, 2:38 p.m. UTC 
The KVM/ARM MMU code doesn't take care of invalidating TLBs before
freeing a {pte,pmd} table. This could cause problems if the page
is reallocated and then speculated into by another CPU.

Reported-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm/kvm/interrupts.S |  2 ++
 arch/arm/kvm/mmu.c        | 42 +++++++++++++++++++++++++++---------------
 2 files changed, 29 insertions(+), 15 deletions(-)

Comments

Catalin Marinas May 2, 2013, 3:13 p.m. UTC | #1 
On Thu, May 02, 2013 at 03:38:58PM +0100, Marc Zyngier wrote:
> diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S
> index f7793df..9e2d906c 100644
> --- a/arch/arm/kvm/interrupts.S
> +++ b/arch/arm/kvm/interrupts.S
...
> -static void clear_pte_entry(pte_t *pte)
> +static void clear_pte_entry(struct kvm *kvm, pte_t *pte, phys_addr_t addr)
>  {
>  	if (pte_present(*pte)) {
>  		kvm_set_pte(pte, __pte(0));
>  		put_page(virt_to_page(pte));
> +		kvm_tlb_flush_vmid_ipa(kvm, addr);
>  	}
>  }
...
>  static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size)
>  {
> -	unmap_range(kvm->arch.pgd, start, size);
> +	unmap_range(kvm, kvm->arch.pgd, start, size);
>  }
>  
>  /**
> @@ -413,6 +425,7 @@ void kvm_free_stage2_pgd(struct kvm *kvm)
>  		return;
>  
>  	unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE);
> +	kvm_tlb_flush_vmid_ipa(kvm, 0);	/* Invalidate TLB ALL */

Do you still need this here if you invalidated each individual pte in
clear_pte_entry()? I think you can remove it from clear_pte_entry() and
just leave it here (more efficient probably) since you wouldn't free the
actual pages pointed at by the pte before unmapping.

>  	free_pages((unsigned long)kvm->arch.pgd, S2_PGD_ORDER);
>  	kvm->arch.pgd = NULL;
>  }
> @@ -675,7 +688,6 @@ static void handle_hva_to_gpa(struct kvm *kvm,
>  static void kvm_unmap_hva_handler(struct kvm *kvm, gpa_t gpa, void *data)
>  {
>  	unmap_stage2_range(kvm, gpa, PAGE_SIZE);
> -	kvm_tlb_flush_vmid_ipa(kvm, gpa);

Here you removed it relying on clear_pte_entry(), I think you could keep
it (see above).
Marc Zyngier May 8, 2013, 10:46 a.m. UTC | #2 
On 02/05/13 16:13, Catalin Marinas wrote:
> On Thu, May 02, 2013 at 03:38:58PM +0100, Marc Zyngier wrote:
>> diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S
>> index f7793df..9e2d906c 100644
>> --- a/arch/arm/kvm/interrupts.S
>> +++ b/arch/arm/kvm/interrupts.S
> ...
>> -static void clear_pte_entry(pte_t *pte)
>> +static void clear_pte_entry(struct kvm *kvm, pte_t *pte, phys_addr_t addr)
>>  {
>>  	if (pte_present(*pte)) {
>>  		kvm_set_pte(pte, __pte(0));
>>  		put_page(virt_to_page(pte));
>> +		kvm_tlb_flush_vmid_ipa(kvm, addr);
>>  	}
>>  }
> ...
>>  static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size)
>>  {
>> -	unmap_range(kvm->arch.pgd, start, size);
>> +	unmap_range(kvm, kvm->arch.pgd, start, size);
>>  }
>>  
>>  /**
>> @@ -413,6 +425,7 @@ void kvm_free_stage2_pgd(struct kvm *kvm)
>>  		return;
>>  
>>  	unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE);
>> +	kvm_tlb_flush_vmid_ipa(kvm, 0);	/* Invalidate TLB ALL */
> 
> Do you still need this here if you invalidated each individual pte in
> clear_pte_entry()? I think you can remove it from clear_pte_entry() and
> just leave it here (more efficient probably) since you wouldn't free the
> actual pages pointed at by the pte before unmapping.

There is two cases we're trying to cater for:
- unmapping a single page from stage2 (page being swapped out, for example)
- unmapping the whole of stage2 (VM exiting)

We cannot loose the "local" operations, but the last one can indeed go.

Thanks,

	M.
diff mbox

Patch

diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S
index f7793df..9e2d906c 100644
--- a/arch/arm/kvm/interrupts.S
+++ b/arch/arm/kvm/interrupts.S
@@ -37,6 +37,8 @@  __kvm_hyp_code_start:
  *
  * void __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa);
  *
+ * Invalidate TLB for the given IPA, or invalidate all if ipa is zero.
+ *
  * We rely on the hardware to broadcast the TLB invalidation to all CPUs
  * inside the inner-shareable domain (which is the case for all v7
  * implementations).  If we come across a non-IS SMP implementation, we'll
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 9657065..4a838db 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -43,7 +43,14 @@  static phys_addr_t hyp_idmap_vector;
 
 static void kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
 {
-	kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, kvm, ipa);
+	/*
+	 * This function also gets called when dealing with HYP page
+	 * tables. As HYP doesn't have an associated struct kvm (and
+	 * the HYP page tables are fairly static), we don't do
+	 * anything there.
+	 */
+	if (kvm)
+		kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, kvm, ipa);
 }
 
 static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
@@ -78,18 +85,20 @@  static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
 	return p;
 }
 
-static void clear_pud_entry(pud_t *pud)
+static void clear_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
 {
 	pmd_t *pmd_table = pmd_offset(pud, 0);
 	pud_clear(pud);
+	kvm_tlb_flush_vmid_ipa(kvm, addr);
 	pmd_free(NULL, pmd_table);
 	put_page(virt_to_page(pud));
 }
 
-static void clear_pmd_entry(pmd_t *pmd)
+static void clear_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
 {
 	pte_t *pte_table = pte_offset_kernel(pmd, 0);
 	pmd_clear(pmd);
+	kvm_tlb_flush_vmid_ipa(kvm, addr);
 	pte_free_kernel(NULL, pte_table);
 	put_page(virt_to_page(pmd));
 }
@@ -100,11 +109,12 @@  static bool pmd_empty(pmd_t *pmd)
 	return page_count(pmd_page) == 1;
 }
 
-static void clear_pte_entry(pte_t *pte)
+static void clear_pte_entry(struct kvm *kvm, pte_t *pte, phys_addr_t addr)
 {
 	if (pte_present(*pte)) {
 		kvm_set_pte(pte, __pte(0));
 		put_page(virt_to_page(pte));
+		kvm_tlb_flush_vmid_ipa(kvm, addr);
 	}
 }
 
@@ -114,7 +124,8 @@  static bool pte_empty(pte_t *pte)
 	return page_count(pte_page) == 1;
 }
 
-static void unmap_range(pgd_t *pgdp, unsigned long long start, u64 size)
+static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
+			unsigned long long start, u64 size)
 {
 	pgd_t *pgd;
 	pud_t *pud;
@@ -138,15 +149,15 @@  static void unmap_range(pgd_t *pgdp, unsigned long long start, u64 size)
 		}
 
 		pte = pte_offset_kernel(pmd, addr);
-		clear_pte_entry(pte);
+		clear_pte_entry(kvm, pte, addr);
 		range = PAGE_SIZE;
 
 		/* If we emptied the pte, walk back up the ladder */
 		if (pte_empty(pte)) {
-			clear_pmd_entry(pmd);
+			clear_pmd_entry(kvm, pmd, addr);
 			range = PMD_SIZE;
 			if (pmd_empty(pmd)) {
-				clear_pud_entry(pud);
+				clear_pud_entry(kvm, pud, addr);
 				range = PUD_SIZE;
 			}
 		}
@@ -165,14 +176,14 @@  void free_boot_hyp_pgd(void)
 	mutex_lock(&kvm_hyp_pgd_mutex);
 
 	if (boot_hyp_pgd) {
-		unmap_range(boot_hyp_pgd, hyp_idmap_start, PAGE_SIZE);
-		unmap_range(boot_hyp_pgd, TRAMPOLINE_VA, PAGE_SIZE);
+		unmap_range(NULL, boot_hyp_pgd, hyp_idmap_start, PAGE_SIZE);
+		unmap_range(NULL, boot_hyp_pgd, TRAMPOLINE_VA, PAGE_SIZE);
 		kfree(boot_hyp_pgd);
 		boot_hyp_pgd = NULL;
 	}
 
 	if (hyp_pgd)
-		unmap_range(hyp_pgd, TRAMPOLINE_VA, PAGE_SIZE);
+		unmap_range(NULL, hyp_pgd, TRAMPOLINE_VA, PAGE_SIZE);
 
 	kfree(init_bounce_page);
 	init_bounce_page = NULL;
@@ -200,9 +211,10 @@  void free_hyp_pgds(void)
 
 	if (hyp_pgd) {
 		for (addr = PAGE_OFFSET; virt_addr_valid(addr); addr += PGDIR_SIZE)
-			unmap_range(hyp_pgd, KERN_TO_HYP(addr), PGDIR_SIZE);
+			unmap_range(NULL, 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);
+			unmap_range(NULL, hyp_pgd, KERN_TO_HYP(addr), PGDIR_SIZE);
+
 		kfree(hyp_pgd);
 		hyp_pgd = NULL;
 	}
@@ -393,7 +405,7 @@  int kvm_alloc_stage2_pgd(struct kvm *kvm)
  */
 static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size)
 {
-	unmap_range(kvm->arch.pgd, start, size);
+	unmap_range(kvm, kvm->arch.pgd, start, size);
 }
 
 /**
@@ -413,6 +425,7 @@  void kvm_free_stage2_pgd(struct kvm *kvm)
 		return;
 
 	unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE);
+	kvm_tlb_flush_vmid_ipa(kvm, 0);	/* Invalidate TLB ALL */
 	free_pages((unsigned long)kvm->arch.pgd, S2_PGD_ORDER);
 	kvm->arch.pgd = NULL;
 }
@@ -675,7 +688,6 @@  static void handle_hva_to_gpa(struct kvm *kvm,
 static void kvm_unmap_hva_handler(struct kvm *kvm, gpa_t gpa, void *data)
 {
 	unmap_stage2_range(kvm, gpa, PAGE_SIZE);
-	kvm_tlb_flush_vmid_ipa(kvm, gpa);
 }
 
 int kvm_unmap_hva(struct kvm *kvm, unsigned long hva)