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Commit 73b1087e authored by Avi Kivity's avatar Avi Kivity Committed by Linus Torvalds
Browse files

[PATCH] KVM: MMU: Report nx faults to the guest 



With the recent guest page fault change, we perform access checks on our
own instead of relying on the cpu.  This means we have to perform the nx
checks as well.

Software like the google toolbar on windows appears to rely on this
somehow.

Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7993ba43

drivers/kvm/mmu.c

+6 −0
Original line number Diff line number Diff line
@@ -143,6 +143,7 @@ static int dbg = 1; 
#define PFERR_PRESENT_MASK (1U << 0)

#define PFERR_WRITE_MASK (1U << 1)

#define PFERR_USER_MASK (1U << 2)

#define PFERR_FETCH_MASK (1U << 4)



#define PT64_ROOT_LEVEL 4

#define PT32_ROOT_LEVEL 2
@@ -168,6 +169,11 @@ static int is_cpuid_PSE36(void) 
	return 1;

}



static int is_nx(struct kvm_vcpu *vcpu)

{

	return vcpu->shadow_efer & EFER_NX;

}



static int is_present_pte(unsigned long pte)

{

	return pte & PT_PRESENT_MASK;

drivers/kvm/paging_tmpl.h

+12 −3
Original line number Diff line number Diff line
@@ -71,7 +71,7 @@ struct guest_walker { 
 */

static int FNAME(walk_addr)(struct guest_walker *walker,

			    struct kvm_vcpu *vcpu, gva_t addr,

			    int write_fault, int user_fault)

			    int write_fault, int user_fault, int fetch_fault)

{

	hpa_t hpa;

	struct kvm_memory_slot *slot;
@@ -123,6 +123,11 @@ static int FNAME(walk_addr)(struct guest_walker *walker, 
		if (user_fault && !(*ptep & PT_USER_MASK))

			goto access_error;



#if PTTYPE == 64

		if (fetch_fault && is_nx(vcpu) && (*ptep & PT64_NX_MASK))

			goto access_error;

#endif



		if (!(*ptep & PT_ACCESSED_MASK))

			*ptep |= PT_ACCESSED_MASK; 	/* avoid rmw */
@@ -169,6 +174,8 @@ static int FNAME(walk_addr)(struct guest_walker *walker, 
		walker->error_code |= PFERR_WRITE_MASK;

	if (user_fault)

		walker->error_code |= PFERR_USER_MASK;

	if (fetch_fault)

		walker->error_code |= PFERR_FETCH_MASK;

	return 0;

}
@@ -372,6 +379,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, 
{

	int write_fault = error_code & PFERR_WRITE_MASK;

	int user_fault = error_code & PFERR_USER_MASK;

	int fetch_fault = error_code & PFERR_FETCH_MASK;

	struct guest_walker walker;

	u64 *shadow_pte;

	int fixed;
@@ -388,7 +396,8 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, 
	/*

	 * Look up the shadow pte for the faulting address.

	 */

	r = FNAME(walk_addr)(&walker, vcpu, addr, write_fault, user_fault);

	r = FNAME(walk_addr)(&walker, vcpu, addr, write_fault, user_fault,

			     fetch_fault);



	/*

	 * The page is not mapped by the guest.  Let the guest handle it.
@@ -437,7 +446,7 @@ 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, 0, 0);

	FNAME(walk_addr)(&walker, vcpu, vaddr, 0, 0, 0);

	guest_pte = *walker.ptep;

	FNAME(release_walker)(&walker);