Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=7993ba43db1c07245ada067791f91dbf018095ac
Commit: 7993ba43db1c07245ada067791f91dbf018095ac
Parent: 6f00e68f210c0407dd666743ce61ae543cfd509d
Author: Avi Kivity <[EMAIL PROTECTED]>
AuthorDate: Fri Jan 26 00:56:41 2007 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Fri Jan 26 13:50:57 2007 -0800
[PATCH] KVM: MMU: Perform access checks in walk_addr()
Check pte permission bits in walk_addr(), instead of scattering the checks
all
over the code. This has the following benefits:
1. We no longer set the accessed bit for accessed which fail permission
checks.
2. Setting the accessed bit is simplified.
3. Under some circumstances, we used to pretend a page fault was fixed when
it would actually fail the access checks. This caused an unnecessary
vmexit.
4. The error code for guest page faults is now correct.
The fix helps netbsd further along booting, and allows kvm to pass the new
mmu
testsuite.
Signed-off-by: Avi Kivity <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
drivers/kvm/mmu.c | 10 ------
drivers/kvm/paging_tmpl.h | 68 +++++++++++++++++++++++++--------------------
2 files changed, 38 insertions(+), 40 deletions(-)
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index c6f9729..a05d060 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -992,16 +992,6 @@ static inline int fix_read_pf(u64 *shadow_ent)
return 0;
}
-static int may_access(u64 pte, int write, int user)
-{
-
- if (user && !(pte & PT_USER_MASK))
- return 0;
- if (write && !(pte & PT_WRITABLE_MASK))
- return 0;
- return 1;
-}
-
static void paging_free(struct kvm_vcpu *vcpu)
{
nonpaging_free(vcpu);
diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index 6bc4195..afcd2a8 100644
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -63,13 +63,15 @@ struct guest_walker {
pt_element_t *ptep;
pt_element_t inherited_ar;
gfn_t gfn;
+ u32 error_code;
};
/*
* Fetch a guest pte for a guest virtual address
*/
-static void FNAME(walk_addr)(struct guest_walker *walker,
- struct kvm_vcpu *vcpu, gva_t addr)
+static int FNAME(walk_addr)(struct guest_walker *walker,
+ struct kvm_vcpu *vcpu, gva_t addr,
+ int write_fault, int user_fault)
{
hpa_t hpa;
struct kvm_memory_slot *slot;
@@ -86,7 +88,7 @@ static void FNAME(walk_addr)(struct guest_walker *walker,
walker->ptep = &vcpu->pdptrs[(addr >> 30) & 3];
root = *walker->ptep;
if (!(root & PT_PRESENT_MASK))
- return;
+ goto not_present;
--walker->level;
}
#endif
@@ -111,11 +113,18 @@ static void FNAME(walk_addr)(struct guest_walker *walker,
ASSERT(((unsigned long)walker->table & PAGE_MASK) ==
((unsigned long)ptep & PAGE_MASK));
- if (is_present_pte(*ptep) && !(*ptep & PT_ACCESSED_MASK))
- *ptep |= PT_ACCESSED_MASK;
-
if (!is_present_pte(*ptep))
- break;
+ goto not_present;
+
+ if (write_fault && !is_writeble_pte(*ptep))
+ if (user_fault || is_write_protection(vcpu))
+ goto access_error;
+
+ if (user_fault && !(*ptep & PT_USER_MASK))
+ goto access_error;
+
+ if (!(*ptep & PT_ACCESSED_MASK))
+ *ptep |= PT_ACCESSED_MASK; /* avoid rmw */
if (walker->level == PT_PAGE_TABLE_LEVEL) {
walker->gfn = (*ptep & PT_BASE_ADDR_MASK)
@@ -146,6 +155,21 @@ static void FNAME(walk_addr)(struct guest_walker *walker,
}
walker->ptep = ptep;
pgprintk("%s: pte %llx\n", __FUNCTION__, (u64)*ptep);
+ return 1;
+
+not_present:
+ walker->error_code = 0;
+ goto err;
+
+access_error:
+ walker->error_code = PFERR_PRESENT_MASK;
+
+err:
+ if (write_fault)
+ walker->error_code |= PFERR_WRITE_MASK;
+ if (user_fault)
+ walker->error_code |= PFERR_USER_MASK;
+ return 0;
}
static void FNAME(release_walker)(struct guest_walker *walker)
@@ -347,7 +371,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t
addr,
u32 error_code)
{
int write_fault = error_code & PFERR_WRITE_MASK;
- int pte_present = error_code & PFERR_PRESENT_MASK;
int user_fault = error_code & PFERR_USER_MASK;
struct guest_walker walker;
u64 *shadow_pte;
@@ -365,19 +388,19 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t
addr,
/*
* Look up the shadow pte for the faulting address.
*/
- FNAME(walk_addr)(&walker, vcpu, addr);
- shadow_pte = FNAME(fetch)(vcpu, addr, &walker);
+ r = FNAME(walk_addr)(&walker, vcpu, addr, write_fault, user_fault);
/*
* The page is not mapped by the guest. Let the guest handle it.
*/
- if (!shadow_pte) {
- pgprintk("%s: not mapped\n", __FUNCTION__);
- inject_page_fault(vcpu, addr, error_code);
+ if (!r) {
+ pgprintk("%s: guest page fault\n", __FUNCTION__);
+ inject_page_fault(vcpu, addr, walker.error_code);
FNAME(release_walker)(&walker);
return 0;
}
+ shadow_pte = FNAME(fetch)(vcpu, addr, &walker);
pgprintk("%s: shadow pte %p %llx\n", __FUNCTION__,
shadow_pte, *shadow_pte);
@@ -399,22 +422,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t
addr,
* mmio: emulate if accessible, otherwise its a guest fault.
*/
if (is_io_pte(*shadow_pte)) {
- if (may_access(*shadow_pte, write_fault, user_fault))
- return 1;
- pgprintk("%s: io work, no access\n", __FUNCTION__);
- inject_page_fault(vcpu, addr,
- error_code | PFERR_PRESENT_MASK);
- kvm_mmu_audit(vcpu, "post page fault (io)");
- return 0;
- }
-
- /*
- * pte not present, guest page fault.
- */
- if (pte_present && !fixed && !write_pt) {
- inject_page_fault(vcpu, addr, error_code);
- kvm_mmu_audit(vcpu, "post page fault (guest)");
- return 0;
+ return 1;
}
++kvm_stat.pf_fixed;
@@ -429,7 +437,7 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t
vaddr)
pt_element_t guest_pte;
gpa_t gpa;
- FNAME(walk_addr)(&walker, vcpu, vaddr);
+ FNAME(walk_addr)(&walker, vcpu, vaddr, 0, 0);
guest_pte = *walker.ptep;
FNAME(release_walker)(&walker);
-
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