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Subject[PATCH 11/15] KVM: MMU: filter out the mmio pfn from the fault pfn
If the page fault is caused by mmio, the gfn can not be found in memslots, and
'bad_pfn' is returned on gfn_to_hva path, so we can use 'bad_pfn' to identify
the mmio page fault.

And, to clarify the meaning of mmio pfn, we return fault page instead of bad
page when the gfn is not allowed to prefetch

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
arch/x86/kvm/mmu.c | 4 ++--
include/linux/kvm_host.h | 5 +++++
virt/kvm/kvm_main.c | 16 ++++++++++++++--
3 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 52d4682..7286d2a 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2133,8 +2133,8 @@ static pfn_t pte_prefetch_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn,

slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, no_dirty_log);
if (!slot) {
- get_page(bad_page);
- return page_to_pfn(bad_page);
+ get_page(fault_page);
+ return page_to_pfn(fault_page);
}

hva = gfn_to_hva_memslot(slot, gfn);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index b9c3299..16d6d3f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -326,12 +326,17 @@ static inline struct kvm_memslots *kvm_memslots(struct kvm *kvm)
static inline int is_error_hpa(hpa_t hpa) { return hpa >> HPA_MSB; }

extern struct page *bad_page;
+extern struct page *fault_page;
+
extern pfn_t bad_pfn;
+extern pfn_t fault_pfn;

int is_error_page(struct page *page);
int is_error_pfn(pfn_t pfn);
int is_hwpoison_pfn(pfn_t pfn);
int is_fault_pfn(pfn_t pfn);
+int is_mmio_pfn(pfn_t pfn);
+int is_invalid_pfn(pfn_t pfn);
int kvm_is_error_hva(unsigned long addr);
int kvm_set_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f78ddb8..93a1ce1 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -97,8 +97,8 @@ static bool largepages_enabled = true;
static struct page *hwpoison_page;
static pfn_t hwpoison_pfn;

-static struct page *fault_page;
-static pfn_t fault_pfn;
+struct page *fault_page;
+pfn_t fault_pfn;

inline int kvm_is_mmio_pfn(pfn_t pfn)
{
@@ -926,6 +926,18 @@ int is_fault_pfn(pfn_t pfn)
}
EXPORT_SYMBOL_GPL(is_fault_pfn);

+int is_mmio_pfn(pfn_t pfn)
+{
+ return pfn == bad_pfn;
+}
+EXPORT_SYMBOL_GPL(is_mmio_pfn);
+
+int is_invalid_pfn(pfn_t pfn)
+{
+ return pfn == hwpoison_pfn || pfn == fault_pfn;
+}
+EXPORT_SYMBOL_GPL(is_invalid_pfn);
+
static inline unsigned long bad_hva(void)
{
return PAGE_OFFSET;
--
1.7.4.4


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