* [patch 1/3] KVM: VMX: remove setting of shadow_base_ptes for EPT
2010-10-05 11:54 [patch 0/3] allow read-only memory mappings Marcelo Tosatti
@ 2010-10-05 11:54 ` Marcelo Tosatti
2010-10-05 11:55 ` [patch 2/3] KVM: dont require read-only host ptes Marcelo Tosatti
2010-10-05 11:55 ` [patch 3/3] KVM: handle " Marcelo Tosatti
2 siblings, 0 replies; 6+ messages in thread
From: Marcelo Tosatti @ 2010-10-05 11:54 UTC (permalink / raw)
To: avi, aarcange, gleb; +Cc: kvm, Marcelo Tosatti
[-- Attachment #1: vmx-remove-base-ptes --]
[-- Type: text/plain, Size: 1145 bytes --]
The EPT present/writable bits use the same position as normal
pagetable bits.
Since direct_map passes ACC_ALL to mmu_set_spte, thus always setting
the writable bit on sptes, use the generic PT_PRESENT shadow_base_pte.
Also pass present/writable error code information from EPT violation
to generic pagefault handler.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Index: kvm/arch/x86/kvm/vmx.c
===================================================================
--- kvm.orig/arch/x86/kvm/vmx.c
+++ kvm/arch/x86/kvm/vmx.c
@@ -3483,7 +3483,7 @@ static int handle_ept_violation(struct k
gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
trace_kvm_page_fault(gpa, exit_qualification);
- return kvm_mmu_page_fault(vcpu, gpa & PAGE_MASK, 0);
+ return kvm_mmu_page_fault(vcpu, gpa, exit_qualification & 0x3);
}
static u64 ept_rsvd_mask(u64 spte, int level)
@@ -4408,8 +4408,6 @@ static int __init vmx_init(void)
if (enable_ept) {
bypass_guest_pf = 0;
- kvm_mmu_set_base_ptes(VMX_EPT_READABLE_MASK |
- VMX_EPT_WRITABLE_MASK);
kvm_mmu_set_mask_ptes(0ull, 0ull, 0ull, 0ull,
VMX_EPT_EXECUTABLE_MASK);
kvm_enable_tdp();
^ permalink raw reply [flat|nested] 6+ messages in thread* [patch 2/3] KVM: dont require read-only host ptes
2010-10-05 11:54 [patch 0/3] allow read-only memory mappings Marcelo Tosatti
2010-10-05 11:54 ` [patch 1/3] KVM: VMX: remove setting of shadow_base_ptes for EPT Marcelo Tosatti
@ 2010-10-05 11:55 ` Marcelo Tosatti
2010-10-05 13:43 ` Gleb Natapov
2010-10-05 11:55 ` [patch 3/3] KVM: handle " Marcelo Tosatti
2 siblings, 1 reply; 6+ messages in thread
From: Marcelo Tosatti @ 2010-10-05 11:55 UTC (permalink / raw)
To: avi, aarcange, gleb; +Cc: kvm, Marcelo Tosatti
[-- Attachment #1: gfn-to-pfn-ronly --]
[-- Type: text/plain, Size: 7088 bytes --]
gfn_to_pfn requires a writable host pte, failing otherwise.
Change it to fallback to read-only "acquision', informing the callers.
Hopefully the ptes are cache-hot so the overhead is minimal.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Index: kvm/arch/ia64/kvm/kvm-ia64.c
===================================================================
--- kvm.orig/arch/ia64/kvm/kvm-ia64.c
+++ kvm/arch/ia64/kvm/kvm-ia64.c
@@ -1589,7 +1589,7 @@ int kvm_arch_prepare_memory_region(struc
return -ENOMEM;
for (i = 0; i < npages; i++) {
- pfn = gfn_to_pfn(kvm, base_gfn + i);
+ pfn = gfn_to_pfn(kvm, base_gfn + i, NULL);
if (!kvm_is_mmio_pfn(pfn)) {
kvm_set_pmt_entry(kvm, base_gfn + i,
pfn << PAGE_SHIFT,
Index: kvm/arch/x86/kvm/mmu.c
===================================================================
--- kvm.orig/arch/x86/kvm/mmu.c
+++ kvm/arch/x86/kvm/mmu.c
@@ -2273,6 +2273,7 @@ static int nonpaging_map(struct kvm_vcpu
{
int r;
int level;
+ int writable;
pfn_t pfn;
unsigned long mmu_seq;
@@ -2289,10 +2290,10 @@ static int nonpaging_map(struct kvm_vcpu
mmu_seq = vcpu->kvm->mmu_notifier_seq;
smp_rmb();
- pfn = gfn_to_pfn(vcpu->kvm, gfn);
+ pfn = gfn_to_pfn(vcpu->kvm, gfn, &writable);
/* mmio */
- if (is_error_pfn(pfn))
+ if (is_error_pfn(pfn) || !writable)
return kvm_handle_bad_page(vcpu->kvm, gfn, pfn);
spin_lock(&vcpu->kvm->mmu_lock);
@@ -2581,6 +2582,8 @@ static int tdp_page_fault(struct kvm_vcp
pfn_t pfn;
int r;
int level;
+ int writable;
+ int write = error_code & PFERR_WRITE_MASK;
gfn_t gfn = gpa >> PAGE_SHIFT;
unsigned long mmu_seq;
@@ -2597,15 +2600,14 @@ static int tdp_page_fault(struct kvm_vcp
mmu_seq = vcpu->kvm->mmu_notifier_seq;
smp_rmb();
- pfn = gfn_to_pfn(vcpu->kvm, gfn);
- if (is_error_pfn(pfn))
+ pfn = gfn_to_pfn(vcpu->kvm, gfn, &writable);
+ if (is_error_pfn(pfn) || !writable)
return kvm_handle_bad_page(vcpu->kvm, gfn, pfn);
spin_lock(&vcpu->kvm->mmu_lock);
if (mmu_notifier_retry(vcpu, mmu_seq))
goto out_unlock;
kvm_mmu_free_some_pages(vcpu);
- r = __direct_map(vcpu, gpa, error_code & PFERR_WRITE_MASK,
- level, gfn, pfn);
+ r = __direct_map(vcpu, gpa, write, level, gfn, pfn);
spin_unlock(&vcpu->kvm->mmu_lock);
return r;
@@ -3043,6 +3045,7 @@ static void mmu_guess_page_from_pte_writ
{
gfn_t gfn;
pfn_t pfn;
+ int writable;
if (!is_present_gpte(gpte))
return;
@@ -3050,9 +3053,9 @@ static void mmu_guess_page_from_pte_writ
vcpu->arch.update_pte.mmu_seq = vcpu->kvm->mmu_notifier_seq;
smp_rmb();
- pfn = gfn_to_pfn(vcpu->kvm, gfn);
+ pfn = gfn_to_pfn(vcpu->kvm, gfn, &writable);
- if (is_error_pfn(pfn)) {
+ if (is_error_pfn(pfn) || !writable) {
kvm_release_pfn_clean(pfn);
return;
}
Index: kvm/arch/x86/kvm/paging_tmpl.h
===================================================================
--- kvm.orig/arch/x86/kvm/paging_tmpl.h
+++ kvm/arch/x86/kvm/paging_tmpl.h
@@ -536,6 +536,7 @@ static int FNAME(page_fault)(struct kvm_
int write_fault = error_code & PFERR_WRITE_MASK;
int user_fault = error_code & PFERR_USER_MASK;
int fetch_fault = error_code & PFERR_FETCH_MASK;
+ int writable;
struct guest_walker walker;
u64 *sptep;
int write_pt = 0;
@@ -573,10 +574,10 @@ static int FNAME(page_fault)(struct kvm_
mmu_seq = vcpu->kvm->mmu_notifier_seq;
smp_rmb();
- pfn = gfn_to_pfn(vcpu->kvm, walker.gfn);
+ pfn = gfn_to_pfn(vcpu->kvm, walker.gfn, &writable);
/* mmio */
- if (is_error_pfn(pfn))
+ if (is_error_pfn(pfn) || !writable)
return kvm_handle_bad_page(vcpu->kvm, walker.gfn, pfn);
spin_lock(&vcpu->kvm->mmu_lock);
Index: kvm/include/linux/kvm_host.h
===================================================================
--- kvm.orig/include/linux/kvm_host.h
+++ kvm/include/linux/kvm_host.h
@@ -302,7 +302,7 @@ void kvm_set_page_accessed(struct page *
pfn_t hva_to_pfn_atomic(struct kvm *kvm, unsigned long addr);
pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn);
-pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn);
+pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn, int *writable);
pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
struct kvm_memory_slot *slot, gfn_t gfn);
int memslot_id(struct kvm *kvm, gfn_t gfn);
Index: kvm/virt/kvm/kvm_main.c
===================================================================
--- kvm.orig/virt/kvm/kvm_main.c
+++ kvm/virt/kvm/kvm_main.c
@@ -948,17 +948,28 @@ unsigned long gfn_to_hva(struct kvm *kvm
}
EXPORT_SYMBOL_GPL(gfn_to_hva);
-static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic)
+static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
+ int *writable)
{
struct page *page[1];
int npages;
pfn_t pfn;
+ if (writable)
+ *writable = 1;
+
if (atomic)
npages = __get_user_pages_fast(addr, 1, 1, page);
else {
might_sleep();
npages = get_user_pages_fast(addr, 1, 1, page);
+
+ /* attempt to map read-only */
+ if (unlikely(npages != 1) && writable) {
+ npages = get_user_pages_fast(addr, 1, 0, page);
+ if (npages == 1)
+ *writable = 0;
+ }
}
if (unlikely(npages != 1)) {
@@ -995,11 +1006,11 @@ return_fault_page:
pfn_t hva_to_pfn_atomic(struct kvm *kvm, unsigned long addr)
{
- return hva_to_pfn(kvm, addr, true);
+ return hva_to_pfn(kvm, addr, true, NULL);
}
EXPORT_SYMBOL_GPL(hva_to_pfn_atomic);
-static pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic)
+static pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic, int *writable)
{
unsigned long addr;
@@ -1009,18 +1020,18 @@ static pfn_t __gfn_to_pfn(struct kvm *kv
return page_to_pfn(bad_page);
}
- return hva_to_pfn(kvm, addr, atomic);
+ return hva_to_pfn(kvm, addr, atomic, writable);
}
pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn)
{
- return __gfn_to_pfn(kvm, gfn, true);
+ return __gfn_to_pfn(kvm, gfn, true, NULL);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn_atomic);
-pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
+pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn, int *writable)
{
- return __gfn_to_pfn(kvm, gfn, false);
+ return __gfn_to_pfn(kvm, gfn, false, writable);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn);
@@ -1028,7 +1039,7 @@ pfn_t gfn_to_pfn_memslot(struct kvm *kvm
struct kvm_memory_slot *slot, gfn_t gfn)
{
unsigned long addr = gfn_to_hva_memslot(slot, gfn);
- return hva_to_pfn(kvm, addr, false);
+ return hva_to_pfn(kvm, addr, false, NULL);
}
int gfn_to_page_many_atomic(struct kvm *kvm, gfn_t gfn, struct page **pages,
@@ -1052,7 +1063,7 @@ struct page *gfn_to_page(struct kvm *kvm
{
pfn_t pfn;
- pfn = gfn_to_pfn(kvm, gfn);
+ pfn = gfn_to_pfn(kvm, gfn, NULL);
if (!kvm_is_mmio_pfn(pfn))
return pfn_to_page(pfn);
Index: kvm/arch/powerpc/kvm/book3s.c
===================================================================
--- kvm.orig/arch/powerpc/kvm/book3s.c
+++ kvm/arch/powerpc/kvm/book3s.c
@@ -468,7 +468,7 @@ pfn_t kvmppc_gfn_to_pfn(struct kvm_vcpu
return pfn;
}
- return gfn_to_pfn(vcpu->kvm, gfn);
+ return gfn_to_pfn(vcpu->kvm, gfn, NULL);
}
/* Book3s_32 CPUs always have 32 bytes cache line size, which Linux assumes. To
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [patch 2/3] KVM: dont require read-only host ptes
2010-10-05 11:55 ` [patch 2/3] KVM: dont require read-only host ptes Marcelo Tosatti
@ 2010-10-05 13:43 ` Gleb Natapov
2010-10-05 13:47 ` Marcelo Tosatti
0 siblings, 1 reply; 6+ messages in thread
From: Gleb Natapov @ 2010-10-05 13:43 UTC (permalink / raw)
To: Marcelo Tosatti; +Cc: avi, aarcange, kvm
On Tue, Oct 05, 2010 at 08:55:00AM -0300, Marcelo Tosatti wrote:
> gfn_to_pfn requires a writable host pte, failing otherwise.
>
> Change it to fallback to read-only "acquision', informing the callers.
>
> Hopefully the ptes are cache-hot so the overhead is minimal.
>
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
>
> Index: kvm/arch/ia64/kvm/kvm-ia64.c
> ===================================================================
> --- kvm.orig/arch/ia64/kvm/kvm-ia64.c
> +++ kvm/arch/ia64/kvm/kvm-ia64.c
> @@ -1589,7 +1589,7 @@ int kvm_arch_prepare_memory_region(struc
> return -ENOMEM;
>
> for (i = 0; i < npages; i++) {
> - pfn = gfn_to_pfn(kvm, base_gfn + i);
> + pfn = gfn_to_pfn(kvm, base_gfn + i, NULL);
> if (!kvm_is_mmio_pfn(pfn)) {
> kvm_set_pmt_entry(kvm, base_gfn + i,
> pfn << PAGE_SHIFT,
> Index: kvm/arch/x86/kvm/mmu.c
> ===================================================================
> --- kvm.orig/arch/x86/kvm/mmu.c
> +++ kvm/arch/x86/kvm/mmu.c
> @@ -2273,6 +2273,7 @@ static int nonpaging_map(struct kvm_vcpu
> {
> int r;
> int level;
> + int writable;
> pfn_t pfn;
> unsigned long mmu_seq;
>
> @@ -2289,10 +2290,10 @@ static int nonpaging_map(struct kvm_vcpu
>
> mmu_seq = vcpu->kvm->mmu_notifier_seq;
> smp_rmb();
> - pfn = gfn_to_pfn(vcpu->kvm, gfn);
> + pfn = gfn_to_pfn(vcpu->kvm, gfn, &writable);
>
> /* mmio */
> - if (is_error_pfn(pfn))
> + if (is_error_pfn(pfn) || !writable)
> return kvm_handle_bad_page(vcpu->kvm, gfn, pfn);
>
> spin_lock(&vcpu->kvm->mmu_lock);
> @@ -2581,6 +2582,8 @@ static int tdp_page_fault(struct kvm_vcp
> pfn_t pfn;
> int r;
> int level;
> + int writable;
> + int write = error_code & PFERR_WRITE_MASK;
> gfn_t gfn = gpa >> PAGE_SHIFT;
> unsigned long mmu_seq;
>
> @@ -2597,15 +2600,14 @@ static int tdp_page_fault(struct kvm_vcp
>
> mmu_seq = vcpu->kvm->mmu_notifier_seq;
> smp_rmb();
> - pfn = gfn_to_pfn(vcpu->kvm, gfn);
> - if (is_error_pfn(pfn))
> + pfn = gfn_to_pfn(vcpu->kvm, gfn, &writable);
> + if (is_error_pfn(pfn) || !writable)
Why would we fail read only access to read only memory? Shouldn't we
check access type here?
--
Gleb.
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [patch 2/3] KVM: dont require read-only host ptes
2010-10-05 13:43 ` Gleb Natapov
@ 2010-10-05 13:47 ` Marcelo Tosatti
0 siblings, 0 replies; 6+ messages in thread
From: Marcelo Tosatti @ 2010-10-05 13:47 UTC (permalink / raw)
To: Gleb Natapov; +Cc: avi, aarcange, kvm
On Tue, Oct 05, 2010 at 03:43:01PM +0200, Gleb Natapov wrote:
> > --- kvm.orig/arch/x86/kvm/mmu.c
> > +++ kvm/arch/x86/kvm/mmu.c
> > @@ -2273,6 +2273,7 @@ static int nonpaging_map(struct kvm_vcpu
> > {
> > int r;
> > int level;
> > + int writable;
> > pfn_t pfn;
> > unsigned long mmu_seq;
> >
> > @@ -2289,10 +2290,10 @@ static int nonpaging_map(struct kvm_vcpu
> >
> > mmu_seq = vcpu->kvm->mmu_notifier_seq;
> > smp_rmb();
> > - pfn = gfn_to_pfn(vcpu->kvm, gfn);
> > + pfn = gfn_to_pfn(vcpu->kvm, gfn, &writable);
> >
> > /* mmio */
> > - if (is_error_pfn(pfn))
> > + if (is_error_pfn(pfn) || !writable)
> > return kvm_handle_bad_page(vcpu->kvm, gfn, pfn);
> >
> > spin_lock(&vcpu->kvm->mmu_lock);
> > @@ -2581,6 +2582,8 @@ static int tdp_page_fault(struct kvm_vcp
> > pfn_t pfn;
> > int r;
> > int level;
> > + int writable;
> > + int write = error_code & PFERR_WRITE_MASK;
> > gfn_t gfn = gpa >> PAGE_SHIFT;
> > unsigned long mmu_seq;
> >
> > @@ -2597,15 +2600,14 @@ static int tdp_page_fault(struct kvm_vcp
> >
> > mmu_seq = vcpu->kvm->mmu_notifier_seq;
> > smp_rmb();
> > - pfn = gfn_to_pfn(vcpu->kvm, gfn);
> > - if (is_error_pfn(pfn))
> > + pfn = gfn_to_pfn(vcpu->kvm, gfn, &writable);
> > + if (is_error_pfn(pfn) || !writable)
> Why would we fail read only access to read only memory? Shouldn't we
> check access type here?
>
> --
> Gleb.
Next patch does that.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [patch 3/3] KVM: handle read-only host ptes
2010-10-05 11:54 [patch 0/3] allow read-only memory mappings Marcelo Tosatti
2010-10-05 11:54 ` [patch 1/3] KVM: VMX: remove setting of shadow_base_ptes for EPT Marcelo Tosatti
2010-10-05 11:55 ` [patch 2/3] KVM: dont require read-only host ptes Marcelo Tosatti
@ 2010-10-05 11:55 ` Marcelo Tosatti
2 siblings, 0 replies; 6+ messages in thread
From: Marcelo Tosatti @ 2010-10-05 11:55 UTC (permalink / raw)
To: avi, aarcange, gleb; +Cc: kvm, Marcelo Tosatti
[-- Attachment #1: unallowed-write-infra --]
[-- Type: text/plain, Size: 6153 bytes --]
Instantiate read-only spte if host pte is read-only, and exit to
userspace if guest attempts to write.
With this in place userspace can mprotect(PROT_READ) guest memory
and handle write attempts.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Index: kvm/arch/x86/kvm/mmu.c
===================================================================
--- kvm.orig/arch/x86/kvm/mmu.c
+++ kvm/arch/x86/kvm/mmu.c
@@ -2205,7 +2205,14 @@ static void direct_pte_prefetch(struct k
__direct_pte_prefetch(vcpu, sp, sptep);
}
-static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
+static int kvm_report_unallowed_write(struct kvm_vcpu *vcpu, gpa_t gpa)
+{
+ vcpu->run->exit_reason = KVM_EXIT_UNALLOWED_WRITE;
+ vcpu->run->unallowed_write.gpa = gpa;
+ return -EPERM;
+}
+
+static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write, int dirty,
int level, gfn_t gfn, pfn_t pfn)
{
struct kvm_shadow_walk_iterator iterator;
@@ -2216,7 +2223,7 @@ static int __direct_map(struct kvm_vcpu
for_each_shadow_entry(vcpu, (u64)gfn << PAGE_SHIFT, iterator) {
if (iterator.level == level) {
mmu_set_spte(vcpu, iterator.sptep, ACC_ALL, ACC_ALL,
- 0, write, 1, &pt_write,
+ 0, write, dirty, &pt_write,
level, gfn, pfn, false, true);
direct_pte_prefetch(vcpu, iterator.sptep);
++vcpu->stat.pf_fixed;
@@ -2269,13 +2276,15 @@ static int kvm_handle_bad_page(struct kv
return 1;
}
-static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
+static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write)
{
int r;
int level;
int writable;
+ int dirty = 1;
pfn_t pfn;
unsigned long mmu_seq;
+ gfn_t gfn = v >> PAGE_SHIFT;
level = mapping_level(vcpu, gfn);
@@ -2293,14 +2302,22 @@ static int nonpaging_map(struct kvm_vcpu
pfn = gfn_to_pfn(vcpu->kvm, gfn, &writable);
/* mmio */
- if (is_error_pfn(pfn) || !writable)
+ if (is_error_pfn(pfn))
return kvm_handle_bad_page(vcpu->kvm, gfn, pfn);
+ if (!writable) {
+ if (write) {
+ kvm_release_pfn_clean(pfn);
+ return kvm_report_unallowed_write(vcpu, v);
+ }
+ /* instantiate read-only spte */
+ dirty = 0;
+ }
spin_lock(&vcpu->kvm->mmu_lock);
if (mmu_notifier_retry(vcpu, mmu_seq))
goto out_unlock;
kvm_mmu_free_some_pages(vcpu);
- r = __direct_map(vcpu, v, write, level, gfn, pfn);
+ r = __direct_map(vcpu, v, write, dirty, level, gfn, pfn);
spin_unlock(&vcpu->kvm->mmu_lock);
@@ -2559,7 +2576,6 @@ static gpa_t nonpaging_gva_to_gpa_nested
static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
u32 error_code)
{
- gfn_t gfn;
int r;
pgprintk("%s: gva %lx error %x\n", __func__, gva, error_code);
@@ -2570,10 +2586,7 @@ static int nonpaging_page_fault(struct k
ASSERT(vcpu);
ASSERT(VALID_PAGE(vcpu->arch.mmu.root_hpa));
- gfn = gva >> PAGE_SHIFT;
-
- return nonpaging_map(vcpu, gva & PAGE_MASK,
- error_code & PFERR_WRITE_MASK, gfn);
+ return nonpaging_map(vcpu, gva, error_code & PFERR_WRITE_MASK);
}
static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa,
@@ -2584,6 +2597,7 @@ static int tdp_page_fault(struct kvm_vcp
int level;
int writable;
int write = error_code & PFERR_WRITE_MASK;
+ int dirty = 1;
gfn_t gfn = gpa >> PAGE_SHIFT;
unsigned long mmu_seq;
@@ -2601,13 +2615,22 @@ static int tdp_page_fault(struct kvm_vcp
mmu_seq = vcpu->kvm->mmu_notifier_seq;
smp_rmb();
pfn = gfn_to_pfn(vcpu->kvm, gfn, &writable);
- if (is_error_pfn(pfn) || !writable)
+ if (is_error_pfn(pfn))
return kvm_handle_bad_page(vcpu->kvm, gfn, pfn);
+ if (!writable) {
+ if (write) {
+ kvm_release_pfn_clean(pfn);
+ return kvm_report_unallowed_write(vcpu, gpa);
+ }
+ /* instantiate read-only spte */
+ dirty = 0;
+ }
+
spin_lock(&vcpu->kvm->mmu_lock);
if (mmu_notifier_retry(vcpu, mmu_seq))
goto out_unlock;
kvm_mmu_free_some_pages(vcpu);
- r = __direct_map(vcpu, gpa, write, level, gfn, pfn);
+ r = __direct_map(vcpu, gpa, write, dirty, level, gfn, pfn);
spin_unlock(&vcpu->kvm->mmu_lock);
return r;
@@ -3261,8 +3284,11 @@ int kvm_mmu_page_fault(struct kvm_vcpu *
enum emulation_result er;
r = vcpu->arch.mmu.page_fault(vcpu, cr2, error_code);
- if (r < 0)
+ if (r < 0) {
+ if (r == -EPERM) /* unallowed write */
+ r = 0;
goto out;
+ }
if (!r) {
r = 1;
Index: kvm/include/linux/kvm.h
===================================================================
--- kvm.orig/include/linux/kvm.h
+++ kvm/include/linux/kvm.h
@@ -161,6 +161,7 @@ struct kvm_pit_config {
#define KVM_EXIT_NMI 16
#define KVM_EXIT_INTERNAL_ERROR 17
#define KVM_EXIT_OSI 18
+#define KVM_EXIT_UNALLOWED_WRITE 19
/* For KVM_EXIT_INTERNAL_ERROR */
#define KVM_INTERNAL_ERROR_EMULATION 1
@@ -264,6 +265,10 @@ struct kvm_run {
struct {
__u64 gprs[32];
} osi;
+ /* KVM_EXIT_UNALLOWED_WRITE */
+ struct {
+ __u64 gpa;
+ } unallowed_write;
/* Fix the size of the union. */
char padding[256];
};
Index: kvm/arch/x86/kvm/paging_tmpl.h
===================================================================
--- kvm.orig/arch/x86/kvm/paging_tmpl.h
+++ kvm/arch/x86/kvm/paging_tmpl.h
@@ -542,6 +542,7 @@ static int FNAME(page_fault)(struct kvm_
int write_pt = 0;
int r;
pfn_t pfn;
+ gpa_t gpa;
int level = PT_PAGE_TABLE_LEVEL;
unsigned long mmu_seq;
@@ -567,6 +568,9 @@ static int FNAME(page_fault)(struct kvm_
return 0;
}
+ gpa = gfn_to_gpa(walker.gfn);
+ gpa |= addr & ~PAGE_MASK;
+
if (walker.level >= PT_DIRECTORY_LEVEL) {
level = min(walker.level, mapping_level(vcpu, walker.gfn));
walker.gfn = walker.gfn & ~(KVM_PAGES_PER_HPAGE(level) - 1);
@@ -577,8 +581,15 @@ static int FNAME(page_fault)(struct kvm_
pfn = gfn_to_pfn(vcpu->kvm, walker.gfn, &writable);
/* mmio */
- if (is_error_pfn(pfn) || !writable)
+ if (is_error_pfn(pfn))
return kvm_handle_bad_page(vcpu->kvm, walker.gfn, pfn);
+ if (!writable) {
+ if (write_fault) {
+ kvm_release_pfn_clean(pfn);
+ return kvm_report_unallowed_write(vcpu, gpa);
+ }
+ walker.pte_access &= ~ACC_WRITE_MASK;
+ }
spin_lock(&vcpu->kvm->mmu_lock);
if (mmu_notifier_retry(vcpu, mmu_seq))
^ permalink raw reply [flat|nested] 6+ messages in thread