[PATCH 01/11] KVM: MMU: rename has_wrprotected_page to mmu_gfn_lpage_is_disallowed

Xiao Guangrong
2016-02-24T10:05:06Z

kvm_lpage_info->write_count is used to detect if the large page mapping
for the gfn on the specified level is allowed, rename it to disallow_lpage
to reflect its purpose, also we rename has_wrprotected_page() to
mmu_gfn_lpage_is_disallowed() to make the code more clearer

Later we will extend this mechanism for page tracking: if the gfn is
tracked then large mapping for that gfn on any level is not allowed.
The new name is more straightforward

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
---
Documentation/virtual/kvm/mmu.txt | 6 +++---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/mmu.c | 25 +++++++++++++------------
arch/x86/kvm/x86.c | 14 ++++++++------
4 files changed, 25 insertions(+), 22 deletions(-)

diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt
index daf9c0f..dda2e93 100644
--- a/Documentation/virtual/kvm/mmu.txt
+++ b/Documentation/virtual/kvm/mmu.txt
@@ -391,11 +391,11 @@ To instantiate a large spte, four constraints must be satisfied:
write-protected pages
- the guest page must be wholly contained by a single memory slot

-To check the last two conditions, the mmu maintains a ->write_count set of
+To check the last two conditions, the mmu maintains a ->disallow_lpage set of
arrays for each memory slot and large page size. Every write protected page
-causes its write_count to be incremented, thus preventing instantiation of
+causes its disallow_lpage to be incremented, thus preventing instantiation of
a large spte. The frames at the end of an unaligned memory slot have
-artificially inflated ->write_counts so they can never be instantiated.
+artificially inflated ->disallow_lpages so they can never be instantiated.

Zapping all pages (page generation count)
=========================================
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 7b54599..1f7fed5 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -644,7 +644,7 @@ struct kvm_vcpu_arch {
};

struct kvm_lpage_info {
- int write_count;
+ int disallow_lpage;
};

struct kvm_arch_memory_slot {
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 07f4c26..06dd4ab 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -789,7 +789,7 @@ static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
slot = __gfn_to_memslot(slots, gfn);
for (i = PT_DIRECTORY_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) {
linfo = lpage_info_slot(gfn, slot, i);
- linfo->write_count += 1;
+ linfo->disallow_lpage += 1;
}
kvm->arch.indirect_shadow_pages++;
}
@@ -807,31 +807,32 @@ static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
slot = __gfn_to_memslot(slots, gfn);
for (i = PT_DIRECTORY_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) {
linfo = lpage_info_slot(gfn, slot, i);
- linfo->write_count -= 1;
- WARN_ON(linfo->write_count < 0);
+ linfo->disallow_lpage -= 1;
+ WARN_ON(linfo->disallow_lpage < 0);
}
kvm->arch.indirect_shadow_pages--;
}

-static int __has_wrprotected_page(gfn_t gfn, int level,
- struct kvm_memory_slot *slot)
+static bool __mmu_gfn_lpage_is_disallowed(gfn_t gfn, int level,
+ struct kvm_memory_slot *slot)
{
struct kvm_lpage_info *linfo;

if (slot) {
linfo = lpage_info_slot(gfn, slot, level);
- return linfo->write_count;
+ return !!linfo->disallow_lpage;
}

- return 1;
+ return true;
}

-static int has_wrprotected_page(struct kvm_vcpu *vcpu, gfn_t gfn, int level)
+static bool mmu_gfn_lpage_is_disallowed(struct kvm_vcpu *vcpu, gfn_t gfn,
+ int level)
{
struct kvm_memory_slot *slot;

slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
- return __has_wrprotected_page(gfn, level, slot);
+ return __mmu_gfn_lpage_is_disallowed(gfn, level, slot);
}

static int host_mapping_level(struct kvm *kvm, gfn_t gfn)
@@ -897,7 +898,7 @@ static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn,
max_level = min(kvm_x86_ops->get_lpage_level(), host_level);

for (level = PT_DIRECTORY_LEVEL; level <= max_level; ++level)
- if (__has_wrprotected_page(large_gfn, level, slot))
+ if (__mmu_gfn_lpage_is_disallowed(large_gfn, level, slot))
break;

return level - 1;
@@ -2503,7 +2504,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
* be fixed if guest refault.
*/
if (level > PT_PAGE_TABLE_LEVEL &&
- has_wrprotected_page(vcpu, gfn, level))
+ mmu_gfn_lpage_is_disallowed(vcpu, gfn, level))
goto done;

spte |= PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE;
@@ -2768,7 +2769,7 @@ static void transparent_hugepage_adjust(struct kvm_vcpu *vcpu,
if (!is_error_noslot_pfn(pfn) && !kvm_is_reserved_pfn(pfn) &&
level == PT_PAGE_TABLE_LEVEL &&
PageTransCompound(pfn_to_page(pfn)) &&
- !has_wrprotected_page(vcpu, gfn, PT_DIRECTORY_LEVEL)) {
+ !mmu_gfn_lpage_is_disallowed(vcpu, gfn, PT_DIRECTORY_LEVEL)) {
unsigned long mask;
/*
* mmu_notifier_retry was successful and we hold the
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2fb92c0..668625e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7879,6 +7879,7 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
int i;

for (i = 0; i < KVM_NR_PAGE_SIZES; ++i) {
+ struct kvm_lpage_info *linfo;
unsigned long ugfn;
int lpages;
int level = i + 1;
@@ -7893,15 +7894,16 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
if (i == 0)
continue;

- slot->arch.lpage_info[i - 1] = kvm_kvzalloc(lpages *
- sizeof(*slot->arch.lpage_info[i - 1]));
- if (!slot->arch.lpage_info[i - 1])
+ linfo = kvm_kvzalloc(lpages * sizeof(*linfo));
+ if (!linfo)
goto out_free;

+ slot->arch.lpage_info[i - 1] = linfo;
+
if (slot->base_gfn & (KVM_PAGES_PER_HPAGE(level) - 1))
- slot->arch.lpage_info[i - 1][0].write_count = 1;
+ linfo[0].disallow_lpage = 1;
if ((slot->base_gfn + npages) & (KVM_PAGES_PER_HPAGE(level) - 1))
- slot->arch.lpage_info[i - 1][lpages - 1].write_count = 1;
+ linfo[lpages - 1].disallow_lpage = 1;
ugfn = slot->userspace_addr >> PAGE_SHIFT;
/*
* If the gfn and userspace address are not aligned wrt each
@@ -7913,7 +7915,7 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
unsigned long j;

for (j = 0; j < lpages; ++j)
- slot->arch.lpage_info[i - 1][j].write_count = 1;
+ linfo[j].disallow_lpage = 1;
}
}

--
1.8.3.1