Re: [PATCH v4 1/5] KVM: MMU: fix release noslot pfn

Xiao Guangrong
2012-10-11T13:06:12Z

On 10/10/2012 11:11 PM, Marcelo Tosatti wrote:

>
> Why does is_error_pfn() return true for mmio spte? Its not an "error",
> after all.
>
> Please kill is_invalid_pfn and use
>
> -> is_error_pfn for checking for errors (mmio spte is not an error pfn,
> its a special pfn)
>
> -> add explicit is_noslot_pfn checks where necessary in the code
> (say to avoid interpreting a noslot_pfn's pfn "address" bits).
>
> (should have noticed this earlier, sorry).

Never mind, your comments are always appreciated! ;)

Marcelo, is it good to you?
(will post it after your check and full test)

diff --git a/arch/powerpc/kvm/book3s_32_mmu_host.c b/arch/powerpc/kvm/book3s_32_mmu_host.c
index 837f13e..3a4d967 100644
--- a/arch/powerpc/kvm/book3s_32_mmu_host.c
+++ b/arch/powerpc/kvm/book3s_32_mmu_host.c
@@ -155,7 +155,7 @@ int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *orig_pte)

/* Get host physical address for gpa */
hpaddr = kvmppc_gfn_to_pfn(vcpu, orig_pte->raddr >> PAGE_SHIFT);
- if (is_error_pfn(hpaddr)) {
+ if (is_error_noslot_pfn(hpaddr)) {
printk(KERN_INFO "Couldn't get guest page for gfn %lx!\n",
orig_pte->eaddr);
r = -EINVAL;
diff --git a/arch/powerpc/kvm/book3s_64_mmu_host.c b/arch/powerpc/kvm/book3s_64_mmu_host.c
index 0688b6b..6c230a2 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_host.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_host.c
@@ -92,7 +92,7 @@ int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *orig_pte)

/* Get host physical address for gpa */
hpaddr = kvmppc_gfn_to_pfn(vcpu, orig_pte->raddr >> PAGE_SHIFT);
- if (is_error_pfn(hpaddr)) {
+ if (is_error_noslot_pfn(hpaddr)) {
printk(KERN_INFO "Couldn't get guest page for gfn %lx!\n", orig_pte->eaddr);
r = -EINVAL;
goto out;
diff --git a/arch/powerpc/kvm/e500_tlb.c b/arch/powerpc/kvm/e500_tlb.c
index ff38b66..4b47eeb 100644
--- a/arch/powerpc/kvm/e500_tlb.c
+++ b/arch/powerpc/kvm/e500_tlb.c
@@ -521,7 +521,7 @@ static inline void kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
if (likely(!pfnmap)) {
unsigned long tsize_pages = 1 << (tsize + 10 - PAGE_SHIFT);
pfn = gfn_to_pfn_memslot(slot, gfn);
- if (is_error_pfn(pfn)) {
+ if (is_error_noslot_pfn(pfn)) {
printk(KERN_ERR "Couldn't get real page for gfn %lx!\n",
(long)gfn);
return;
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 56c0e39..54c3557 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2699,7 +2699,7 @@ static void transparent_hugepage_adjust(struct kvm_vcpu *vcpu,
* PT_PAGE_TABLE_LEVEL and there would be no adjustment done
* here.
*/
- if (!is_error_pfn(pfn) && !kvm_is_mmio_pfn(pfn) &&
+ if (!is_error_noslot_pfn(pfn) && !kvm_is_mmio_pfn(pfn) &&
level == PT_PAGE_TABLE_LEVEL &&
PageTransCompound(pfn_to_page(pfn)) &&
!has_wrprotected_page(vcpu->kvm, gfn, PT_DIRECTORY_LEVEL)) {
@@ -2733,7 +2733,7 @@ static bool handle_abnormal_pfn(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn,
bool ret = true;

/* The pfn is invalid, report the error! */
- if (unlikely(is_invalid_pfn(pfn))) {
+ if (unlikely(is_error_pfn(pfn))) {
*ret_val = kvm_handle_bad_page(vcpu, gfn, pfn);
goto exit;
}
diff --git a/arch/x86/kvm/mmu_audit.c b/arch/x86/kvm/mmu_audit.c
index daff69e..7709a75 100644
--- a/arch/x86/kvm/mmu_audit.c
+++ b/arch/x86/kvm/mmu_audit.c
@@ -116,7 +116,7 @@ static void audit_mappings(struct kvm_vcpu *vcpu, u64 *sptep, int level)
gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);
pfn = gfn_to_pfn_atomic(vcpu->kvm, gfn);

- if (is_error_pfn(pfn))
+ if (is_error_noslot_pfn(pfn))
return;

hpa = pfn << PAGE_SHIFT;
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index f887e4c..89f3241 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -323,7 +323,7 @@ FNAME(prefetch_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
protect_clean_gpte(&pte_access, gpte);
pfn = pte_prefetch_gfn_to_pfn(vcpu, gfn,
no_dirty_log && (pte_access & ACC_WRITE_MASK));
- if (is_invalid_pfn(pfn))
+ if (is_error_pfn(pfn))
return false;

/*
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1eefebe..91f8f71 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4502,7 +4502,7 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gva_t gva)
* instruction -> ...
*/
pfn = gfn_to_pfn(vcpu->kvm, gpa_to_gfn(gpa));
- if (!is_error_pfn(pfn)) {
+ if (!is_error_noslot_pfn(pfn)) {
kvm_release_pfn_clean(pfn);
return true;
}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 93bfc9f..45ff7c6 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -58,28 +58,30 @@

/*
* For the normal pfn, the highest 12 bits should be zero,
- * so we can mask these bits to indicate the error.
+ * so we can mask bit 62 ~ bit 52 to indicate the error pfn,
+ * mask bit 63 to indicate the noslot pfn.
*/
-#define KVM_PFN_ERR_MASK (0xfffULL << 52)
+#define KVM_PFN_ERR_MASK (0x7ffULL << 52)
+#define KVM_PFN_ERR_NOSLOT_MASK (0xfffULL << 52)
+#define KVM_PFN_NOSLOT (0x1ULL << 63)

#define KVM_PFN_ERR_FAULT (KVM_PFN_ERR_MASK)
#define KVM_PFN_ERR_HWPOISON (KVM_PFN_ERR_MASK + 1)
-#define KVM_PFN_ERR_BAD (KVM_PFN_ERR_MASK + 2)
-#define KVM_PFN_ERR_RO_FAULT (KVM_PFN_ERR_MASK + 3)
+#define KVM_PFN_ERR_RO_FAULT (KVM_PFN_ERR_MASK + 2)

static inline bool is_error_pfn(pfn_t pfn)
{
return !!(pfn & KVM_PFN_ERR_MASK);
}

-static inline bool is_noslot_pfn(pfn_t pfn)
+static inline bool is_error_noslot_pfn(pfn_t pfn)
{
- return pfn == KVM_PFN_ERR_BAD;
+ return !!(pfn & KVM_PFN_ERR_NOSLOT_MASK);
}

-static inline bool is_invalid_pfn(pfn_t pfn)
+static inline bool is_noslot_pfn(pfn_t pfn)
{
- return !is_noslot_pfn(pfn) && is_error_pfn(pfn);
+ return pfn == KVM_PFN_NOSLOT;
}

#define KVM_HVA_ERR_BAD (PAGE_OFFSET)
diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index 037cb67..5534f46 100644
--- a/virt/kvm/iommu.c
+++ b/virt/kvm/iommu.c
@@ -52,7 +52,7 @@ static pfn_t kvm_pin_pages(struct kvm_memory_slot *slot, gfn_t gfn,
end_gfn = gfn + (size >> PAGE_SHIFT);
gfn += 1;

- if (is_error_pfn(pfn))
+ if (is_error_noslot_pfn(pfn))
return pfn;

while (gfn < end_gfn)
@@ -106,7 +106,7 @@ int kvm_iommu_map_pages(struct kvm *kvm, struct kvm_memory_slot *slot)
* important because we unmap and unpin in 4kb steps later.
*/
pfn = kvm_pin_pages(slot, gfn, page_size);
- if (is_error_pfn(pfn)) {
+ if (is_error_noslot_pfn(pfn)) {
gfn += 1;
continue;
}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a65bc02..e26a55f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1208,7 +1208,7 @@ __gfn_to_pfn_memslot(struct kvm_memory_slot *slot, gfn_t gfn, bool atomic,
return KVM_PFN_ERR_RO_FAULT;

if (kvm_is_error_hva(addr))
- return KVM_PFN_ERR_BAD;
+ return KVM_PFN_NOSLOT;

/* Do not map writable pfn in the readonly memslot. */
if (writable && memslot_is_readonly(slot)) {
@@ -1290,7 +1290,7 @@ EXPORT_SYMBOL_GPL(gfn_to_page_many_atomic);

static struct page *kvm_pfn_to_page(pfn_t pfn)
{
- if (is_error_pfn(pfn))
+ if (is_error_noslot_pfn(pfn))
return KVM_ERR_PTR_BAD_PAGE;

if (kvm_is_mmio_pfn(pfn)) {
@@ -1322,7 +1322,7 @@ EXPORT_SYMBOL_GPL(kvm_release_page_clean);

void kvm_release_pfn_clean(pfn_t pfn)
{
- if (!is_error_pfn(pfn) && !kvm_is_mmio_pfn(pfn))
+ if (!is_error_noslot_pfn(pfn) && !kvm_is_mmio_pfn(pfn))
put_page(pfn_to_page(pfn));
}
EXPORT_SYMBOL_GPL(kvm_release_pfn_clean);