[PATCH BACKPORT 3.17-4.4 0/4] MIPS: KVM: Fix MMU/TLB management issues

[PATCH BACKPORT 3.17-4.4 0/4] MIPS: KVM: Fix MMU/TLB management issues

[James Hogan]

These patches backport fixes for several issues in the management of
MIPS KVM TLB faults to 4.4, and should apply back to 3.17 too.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: <stable@vger.kernel.org>

James Hogan (4):
  MIPS: KVM: Fix mapped fault broken commpage handling
  MIPS: KVM: Add missing gfn range check
  MIPS: KVM: Fix gfn range check in kseg0 tlb faults
  MIPS: KVM: Propagate kseg0/mapped tlb fault errors

 arch/mips/kvm/emulate.c | 40 +++++++++++++++++--------
 arch/mips/kvm/tlb.c     | 68 +++++++++++++++++++++++++++---------------
 2 files changed, 72 insertions(+), 36 deletions(-)

-- 
git-series 0.8.8

[PATCH BACKPORT 3.17-4.4 1/4] MIPS: KVM: Fix mapped fault broken commpage handling

[James Hogan]

commit c604cffa93478f8888bec62b23d6073dad03d43a upstream.

kvm_mips_handle_mapped_seg_tlb_fault() appears to map the guest page at
virtual address 0 to PFN 0 if the guest has created its own mapping
there. The intention is unclear, but it may have been an attempt to
protect the zero page from being mapped to anything but the comm page in
code paths you wouldn't expect from genuine commpage accesses (guest
kernel mode cache instructions on that address, hitting trapping
instructions when executing from that address with a coincidental TLB
eviction during the KVM handling, and guest user mode accesses to that
address).

Fix this to check for mappings exactly at KVM_GUEST_COMMPAGE_ADDR (it
may not be at address 0 since commit 42aa12e74e91 ("MIPS: KVM: Move
commpage so 0x0 is unmapped")), and set the corresponding EntryLo to be
interpreted as 0 (invalid).

Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[james.hogan@imgtec.com: Backport to v3.17.y - v4.4.y]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
---
 arch/mips/kvm/tlb.c | 45 ++++++++++++++++++++++++++-------------------
 1 file changed, 26 insertions(+), 19 deletions(-)

diff --git a/arch/mips/kvm/tlb.c b/arch/mips/kvm/tlb.c
index aed0ac2a4972..d3c5715426c4 100644
--- a/arch/mips/kvm/tlb.c
+++ b/arch/mips/kvm/tlb.c
@@ -361,24 +361,31 @@ int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
 	unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0;
 	struct kvm *kvm = vcpu->kvm;
 	pfn_t pfn0, pfn1;
+	long tlb_lo[2];
 
-	if ((tlb->tlb_hi & VPN2_MASK) == 0) {
-		pfn0 = 0;
-		pfn1 = 0;
-	} else {
-		if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb->tlb_lo0)
-					   >> PAGE_SHIFT) < 0)
-			return -1;
-
-		if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb->tlb_lo1)
-					   >> PAGE_SHIFT) < 0)
-			return -1;
-
-		pfn0 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb->tlb_lo0)
-					    >> PAGE_SHIFT];
-		pfn1 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb->tlb_lo1)
-					    >> PAGE_SHIFT];
-	}
+	tlb_lo[0] = tlb->tlb_lo0;
+	tlb_lo[1] = tlb->tlb_lo1;
+
+	/*
+	 * The commpage address must not be mapped to anything else if the guest
+	 * TLB contains entries nearby, or commpage accesses will break.
+	 */
+	if (!((tlb->tlb_hi ^ KVM_GUEST_COMMPAGE_ADDR) &
+			VPN2_MASK & (PAGE_MASK << 1)))
+		tlb_lo[(KVM_GUEST_COMMPAGE_ADDR >> PAGE_SHIFT) & 1] = 0;
+
+	if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[0])
+				   >> PAGE_SHIFT) < 0)
+		return -1;
+
+	if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[1])
+				   >> PAGE_SHIFT) < 0)
+		return -1;
+
+	pfn0 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[0])
+				    >> PAGE_SHIFT];
+	pfn1 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[1])
+				    >> PAGE_SHIFT];
 
 	if (hpa0)
 		*hpa0 = pfn0 << PAGE_SHIFT;
@@ -391,9 +398,9 @@ int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
 					       kvm_mips_get_kernel_asid(vcpu) :
 					       kvm_mips_get_user_asid(vcpu));
 	entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) | (0x3 << 3) |
-		   (tlb->tlb_lo0 & MIPS3_PG_D) | (tlb->tlb_lo0 & MIPS3_PG_V);
+		   (tlb_lo[0] & MIPS3_PG_D) | (tlb_lo[0] & MIPS3_PG_V);
 	entrylo1 = mips3_paddr_to_tlbpfn(pfn1 << PAGE_SHIFT) | (0x3 << 3) |
-		   (tlb->tlb_lo1 & MIPS3_PG_D) | (tlb->tlb_lo1 & MIPS3_PG_V);
+		   (tlb_lo[1] & MIPS3_PG_D) | (tlb_lo[1] & MIPS3_PG_V);
 
 	kvm_debug("@ %#lx tlb_lo0: 0x%08lx tlb_lo1: 0x%08lx\n", vcpu->arch.pc,
 		  tlb->tlb_lo0, tlb->tlb_lo1);
-- 
git-series 0.8.8

Patch "[PATCH BACKPORT 3.17-4.4 1/4] MIPS: KVM: Fix mapped fault broken commpage handling" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    [PATCH BACKPORT 3.17-4.4 1/4] MIPS: KVM: Fix mapped fault broken commpage handling

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mips-kvm-fix-mapped-fault-broken-commpage-handling.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From james.hogan@imgtec.com  Thu Aug 18 11:44:25 2016
From: James Hogan <james.hogan@imgtec.com>
Date: Thu, 18 Aug 2016 10:05:29 +0100
Subject: [PATCH BACKPORT 3.17-4.4 1/4] MIPS: KVM: Fix mapped fault broken commpage handling
To: <stable@vger.kernel.org>
Cc: James Hogan <james.hogan@imgtec.com>, Paolo Bonzini <pbonzini@redhat.com>, Radim Krčmář <rkrcmar@redhat.com>, Ralf Baechle <ralf@linux-mips.org>, <linux-mips@linux-mips.org>, <kvm@vger.kernel.org>
Message-ID: <68df6d553f95e9f40311c92f7e010d90a329843a.1471018436.git-series.james.hogan@imgtec.com>

From: James Hogan <james.hogan@imgtec.com>

commit c604cffa93478f8888bec62b23d6073dad03d43a upstream.

kvm_mips_handle_mapped_seg_tlb_fault() appears to map the guest page at
virtual address 0 to PFN 0 if the guest has created its own mapping
there. The intention is unclear, but it may have been an attempt to
protect the zero page from being mapped to anything but the comm page in
code paths you wouldn't expect from genuine commpage accesses (guest
kernel mode cache instructions on that address, hitting trapping
instructions when executing from that address with a coincidental TLB
eviction during the KVM handling, and guest user mode accesses to that
address).

Fix this to check for mappings exactly at KVM_GUEST_COMMPAGE_ADDR (it
may not be at address 0 since commit 42aa12e74e91 ("MIPS: KVM: Move
commpage so 0x0 is unmapped")), and set the corresponding EntryLo to be
interpreted as 0 (invalid).

Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[james.hogan@imgtec.com: Backport to v3.17.y - v4.4.y]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/mips/kvm/tlb.c |   45 ++++++++++++++++++++++++++-------------------
 1 file changed, 26 insertions(+), 19 deletions(-)

--- a/arch/mips/kvm/tlb.c
+++ b/arch/mips/kvm/tlb.c
@@ -361,24 +361,31 @@ int kvm_mips_handle_mapped_seg_tlb_fault
 	unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0;
 	struct kvm *kvm = vcpu->kvm;
 	pfn_t pfn0, pfn1;
+	long tlb_lo[2];
 
-	if ((tlb->tlb_hi & VPN2_MASK) == 0) {
-		pfn0 = 0;
-		pfn1 = 0;
-	} else {
-		if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb->tlb_lo0)
-					   >> PAGE_SHIFT) < 0)
-			return -1;
-
-		if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb->tlb_lo1)
-					   >> PAGE_SHIFT) < 0)
-			return -1;
-
-		pfn0 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb->tlb_lo0)
-					    >> PAGE_SHIFT];
-		pfn1 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb->tlb_lo1)
-					    >> PAGE_SHIFT];
-	}
+	tlb_lo[0] = tlb->tlb_lo0;
+	tlb_lo[1] = tlb->tlb_lo1;
+
+	/*
+	 * The commpage address must not be mapped to anything else if the guest
+	 * TLB contains entries nearby, or commpage accesses will break.
+	 */
+	if (!((tlb->tlb_hi ^ KVM_GUEST_COMMPAGE_ADDR) &
+			VPN2_MASK & (PAGE_MASK << 1)))
+		tlb_lo[(KVM_GUEST_COMMPAGE_ADDR >> PAGE_SHIFT) & 1] = 0;
+
+	if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[0])
+				   >> PAGE_SHIFT) < 0)
+		return -1;
+
+	if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[1])
+				   >> PAGE_SHIFT) < 0)
+		return -1;
+
+	pfn0 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[0])
+				    >> PAGE_SHIFT];
+	pfn1 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[1])
+				    >> PAGE_SHIFT];
 
 	if (hpa0)
 		*hpa0 = pfn0 << PAGE_SHIFT;
@@ -391,9 +398,9 @@ int kvm_mips_handle_mapped_seg_tlb_fault
 					       kvm_mips_get_kernel_asid(vcpu) :
 					       kvm_mips_get_user_asid(vcpu));
 	entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) | (0x3 << 3) |
-		   (tlb->tlb_lo0 & MIPS3_PG_D) | (tlb->tlb_lo0 & MIPS3_PG_V);
+		   (tlb_lo[0] & MIPS3_PG_D) | (tlb_lo[0] & MIPS3_PG_V);
 	entrylo1 = mips3_paddr_to_tlbpfn(pfn1 << PAGE_SHIFT) | (0x3 << 3) |
-		   (tlb->tlb_lo1 & MIPS3_PG_D) | (tlb->tlb_lo1 & MIPS3_PG_V);
+		   (tlb_lo[1] & MIPS3_PG_D) | (tlb_lo[1] & MIPS3_PG_V);
 
 	kvm_debug("@ %#lx tlb_lo0: 0x%08lx tlb_lo1: 0x%08lx\n", vcpu->arch.pc,
 		  tlb->tlb_lo0, tlb->tlb_lo1);


Patches currently in stable-queue which might be from james.hogan@imgtec.com are

queue-4.4/mips-kvm-add-missing-gfn-range-check.patch
queue-4.4/mips-kvm-propagate-kseg0-mapped-tlb-fault-errors.patch
queue-4.4/mips-kvm-fix-mapped-fault-broken-commpage-handling.patch
queue-4.4/mips-kvm-fix-gfn-range-check-in-kseg0-tlb-faults.patch

[PATCH BACKPORT 3.17-4.4 2/4] MIPS: KVM: Add missing gfn range check

[James Hogan]

commit 8985d50382359e5bf118fdbefc859d0dbf6cebc7 upstream.

kvm_mips_handle_mapped_seg_tlb_fault() calculates the guest frame number
based on the guest TLB EntryLo values, however it is not range checked
to ensure it lies within the guest_pmap. If the physical memory the
guest refers to is out of range then dump the guest TLB and emit an
internal error.

Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[james.hogan@imgtec.com: Backport to v3.17.y - v4.4.y]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
---
 arch/mips/kvm/tlb.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/arch/mips/kvm/tlb.c b/arch/mips/kvm/tlb.c
index d3c5715426c4..59e885fa4c65 100644
--- a/arch/mips/kvm/tlb.c
+++ b/arch/mips/kvm/tlb.c
@@ -361,6 +361,7 @@ int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
 	unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0;
 	struct kvm *kvm = vcpu->kvm;
 	pfn_t pfn0, pfn1;
+	gfn_t gfn0, gfn1;
 	long tlb_lo[2];
 
 	tlb_lo[0] = tlb->tlb_lo0;
@@ -374,18 +375,24 @@ int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
 			VPN2_MASK & (PAGE_MASK << 1)))
 		tlb_lo[(KVM_GUEST_COMMPAGE_ADDR >> PAGE_SHIFT) & 1] = 0;
 
-	if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[0])
-				   >> PAGE_SHIFT) < 0)
+	gfn0 = mips3_tlbpfn_to_paddr(tlb_lo[0]) >> PAGE_SHIFT;
+	gfn1 = mips3_tlbpfn_to_paddr(tlb_lo[1]) >> PAGE_SHIFT;
+	if (gfn0 >= kvm->arch.guest_pmap_npages ||
+	    gfn1 >= kvm->arch.guest_pmap_npages) {
+		kvm_err("%s: Invalid gfn: [%#llx, %#llx], EHi: %#lx\n",
+			__func__, gfn0, gfn1, tlb->tlb_hi);
+		kvm_mips_dump_guest_tlbs(vcpu);
+		return -1;
+	}
+
+	if (kvm_mips_map_page(kvm, gfn0) < 0)
 		return -1;
 
-	if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[1])
-				   >> PAGE_SHIFT) < 0)
+	if (kvm_mips_map_page(kvm, gfn1) < 0)
 		return -1;
 
-	pfn0 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[0])
-				    >> PAGE_SHIFT];
-	pfn1 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[1])
-				    >> PAGE_SHIFT];
+	pfn0 = kvm->arch.guest_pmap[gfn0];
+	pfn1 = kvm->arch.guest_pmap[gfn1];
 
 	if (hpa0)
 		*hpa0 = pfn0 << PAGE_SHIFT;
-- 
git-series 0.8.8

Patch "[PATCH BACKPORT 3.17-4.4 2/4] MIPS: KVM: Add missing gfn range check" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    [PATCH BACKPORT 3.17-4.4 2/4] MIPS: KVM: Add missing gfn range check

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mips-kvm-add-missing-gfn-range-check.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From james.hogan@imgtec.com  Thu Aug 18 11:44:38 2016
From: James Hogan <james.hogan@imgtec.com>
Date: Thu, 18 Aug 2016 10:05:30 +0100
Subject: [PATCH BACKPORT 3.17-4.4 2/4] MIPS: KVM: Add missing gfn range check
To: <stable@vger.kernel.org>
Cc: James Hogan <james.hogan@imgtec.com>, Paolo Bonzini <pbonzini@redhat.com>, Radim Krčmář <rkrcmar@redhat.com>, Ralf Baechle <ralf@linux-mips.org>, <linux-mips@linux-mips.org>, <kvm@vger.kernel.org>
Message-ID: <5ae3371dc11534460b722864ea8c6ef27e8506d1.1471018436.git-series.james.hogan@imgtec.com>

From: James Hogan <james.hogan@imgtec.com>

commit 8985d50382359e5bf118fdbefc859d0dbf6cebc7 upstream.

kvm_mips_handle_mapped_seg_tlb_fault() calculates the guest frame number
based on the guest TLB EntryLo values, however it is not range checked
to ensure it lies within the guest_pmap. If the physical memory the
guest refers to is out of range then dump the guest TLB and emit an
internal error.

Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[james.hogan@imgtec.com: Backport to v3.17.y - v4.4.y]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/mips/kvm/tlb.c |   23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

--- a/arch/mips/kvm/tlb.c
+++ b/arch/mips/kvm/tlb.c
@@ -361,6 +361,7 @@ int kvm_mips_handle_mapped_seg_tlb_fault
 	unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0;
 	struct kvm *kvm = vcpu->kvm;
 	pfn_t pfn0, pfn1;
+	gfn_t gfn0, gfn1;
 	long tlb_lo[2];
 
 	tlb_lo[0] = tlb->tlb_lo0;
@@ -374,18 +375,24 @@ int kvm_mips_handle_mapped_seg_tlb_fault
 			VPN2_MASK & (PAGE_MASK << 1)))
 		tlb_lo[(KVM_GUEST_COMMPAGE_ADDR >> PAGE_SHIFT) & 1] = 0;
 
-	if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[0])
-				   >> PAGE_SHIFT) < 0)
+	gfn0 = mips3_tlbpfn_to_paddr(tlb_lo[0]) >> PAGE_SHIFT;
+	gfn1 = mips3_tlbpfn_to_paddr(tlb_lo[1]) >> PAGE_SHIFT;
+	if (gfn0 >= kvm->arch.guest_pmap_npages ||
+	    gfn1 >= kvm->arch.guest_pmap_npages) {
+		kvm_err("%s: Invalid gfn: [%#llx, %#llx], EHi: %#lx\n",
+			__func__, gfn0, gfn1, tlb->tlb_hi);
+		kvm_mips_dump_guest_tlbs(vcpu);
 		return -1;
+	}
 
-	if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[1])
-				   >> PAGE_SHIFT) < 0)
+	if (kvm_mips_map_page(kvm, gfn0) < 0)
 		return -1;
 
-	pfn0 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[0])
-				    >> PAGE_SHIFT];
-	pfn1 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[1])
-				    >> PAGE_SHIFT];
+	if (kvm_mips_map_page(kvm, gfn1) < 0)
+		return -1;
+
+	pfn0 = kvm->arch.guest_pmap[gfn0];
+	pfn1 = kvm->arch.guest_pmap[gfn1];
 
 	if (hpa0)
 		*hpa0 = pfn0 << PAGE_SHIFT;


Patches currently in stable-queue which might be from james.hogan@imgtec.com are

queue-4.4/mips-kvm-add-missing-gfn-range-check.patch
queue-4.4/mips-kvm-propagate-kseg0-mapped-tlb-fault-errors.patch
queue-4.4/mips-kvm-fix-mapped-fault-broken-commpage-handling.patch
queue-4.4/mips-kvm-fix-gfn-range-check-in-kseg0-tlb-faults.patch

Re: [PATCH BACKPORT 3.17-4.4 2/4] MIPS: KVM: Add missing gfn range check

[Levin, Alexander]

On 08/18/2016 05:05 AM, James Hogan wrote:
> commit 8985d50382359e5bf118fdbefc859d0dbf6cebc7 upstream.
> 
> kvm_mips_handle_mapped_seg_tlb_fault() calculates the guest frame number
> based on the guest TLB EntryLo values, however it is not range checked
> to ensure it lies within the guest_pmap. If the physical memory the
> guest refers to is out of range then dump the guest TLB and emit an
> internal error.
> 
> Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.")
> Signed-off-by: James Hogan <james.hogan@imgtec.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: "Radim Krčmář" <rkrcmar@redhat.com>
> Cc: Ralf Baechle <ralf@linux-mips.org>
> Cc: linux-mips@linux-mips.org
> Cc: kvm@vger.kernel.org
> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> [james.hogan@imgtec.com: Backport to v3.17.y - v4.4.y]
> Signed-off-by: James Hogan <james.hogan@imgtec.com>

Hey James,

Thanks for the backport!

Applying this one seems to fail with:

$ git apply --reject [PATCH BACKPORT 3.17-4.4 1_4] MIPS: KVM: Fix mapped
fault broken commpage handling - James Hogan <james.hogan@imgtec.com> -
2016-08-18 0505.eml
Checking patch arch/mips/kvm/tlb.c...
error: while searching for:
	unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0;
	struct kvm *kvm = vcpu->kvm;
	pfn_t pfn0, pfn1;
	long tlb_lo[2];

	tlb_lo[0] = tlb->tlb_lo0;

error: patch failed: arch/mips/kvm/tlb.c:361
error: while searching for:
			VPN2_MASK & (PAGE_MASK << 1)))
		tlb_lo[(KVM_GUEST_COMMPAGE_ADDR >> PAGE_SHIFT) & 1] = 0;

	if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[0])
				   >> PAGE_SHIFT) < 0)
		return -1;

	if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[1])
				   >> PAGE_SHIFT) < 0)
		return -1;

	pfn0 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[0])
				    >> PAGE_SHIFT];
	pfn1 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[1])
				    >> PAGE_SHIFT];

	if (hpa0)
		*hpa0 = pfn0 << PAGE_SHIFT;

error: patch failed: arch/mips/kvm/tlb.c:374
Applying patch arch/mips/kvm/tlb.c with 2 rejects...
Rejected hunk #1.
Rejected hunk #2.


Thanks,
Sasha

Re: [PATCH BACKPORT 3.17-4.4 2/4] MIPS: KVM: Add missing gfn range check

[Levin, Alexander]

On 08/18/2016 07:45 AM, Sasha Levin wrote:
> On 08/18/2016 05:05 AM, James Hogan wrote:
>> > commit 8985d50382359e5bf118fdbefc859d0dbf6cebc7 upstream.
>> > 
>> > kvm_mips_handle_mapped_seg_tlb_fault() calculates the guest frame number
>> > based on the guest TLB EntryLo values, however it is not range checked
>> > to ensure it lies within the guest_pmap. If the physical memory the
>> > guest refers to is out of range then dump the guest TLB and emit an
>> > internal error.
>> > 
>> > Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.")
>> > Signed-off-by: James Hogan <james.hogan@imgtec.com>
>> > Cc: Paolo Bonzini <pbonzini@redhat.com>
>> > Cc: "Radim Krčmář" <rkrcmar@redhat.com>
>> > Cc: Ralf Baechle <ralf@linux-mips.org>
>> > Cc: linux-mips@linux-mips.org
>> > Cc: kvm@vger.kernel.org
>> > Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
>> > [james.hogan@imgtec.com: Backport to v3.17.y - v4.4.y]
>> > Signed-off-by: James Hogan <james.hogan@imgtec.com>
> Hey James,
> 
> Thanks for the backport!
> 
> Applying this one seems to fail with:

*Applying to this one to 4.1, sorry.


Thanks,
Sasha

Re: [PATCH BACKPORT 3.17-4.4 2/4] MIPS: KVM: Add missing gfn range check

[James Hogan]

[-- Attachment #1: Type: text/plain, Size: 2488 bytes --]

Hi Sasha,

On Thu, Aug 18, 2016 at 07:45:33AM -0400, Levin, Alexander wrote:
> On 08/18/2016 05:05 AM, James Hogan wrote:
> > commit 8985d50382359e5bf118fdbefc859d0dbf6cebc7 upstream.
> > 
> > kvm_mips_handle_mapped_seg_tlb_fault() calculates the guest frame number
> > based on the guest TLB EntryLo values, however it is not range checked
> > to ensure it lies within the guest_pmap. If the physical memory the
> > guest refers to is out of range then dump the guest TLB and emit an
> > internal error.
> > 
> > Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.")
> > Signed-off-by: James Hogan <james.hogan@imgtec.com>
> > Cc: Paolo Bonzini <pbonzini@redhat.com>
> > Cc: "Radim Krčmář" <rkrcmar@redhat.com>
> > Cc: Ralf Baechle <ralf@linux-mips.org>
> > Cc: linux-mips@linux-mips.org
> > Cc: kvm@vger.kernel.org
> > Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> > [james.hogan@imgtec.com: Backport to v3.17.y - v4.4.y]
> > Signed-off-by: James Hogan <james.hogan@imgtec.com>
> 
> Hey James,
> 
> Thanks for the backport!
> 
> Applying this one seems to fail with:
> 
> $ git apply --reject [PATCH BACKPORT 3.17-4.4 1_4] MIPS: KVM: Fix mapped
> fault broken commpage handling - James Hogan <james.hogan@imgtec.com> -
> 2016-08-18 0505.eml
> Checking patch arch/mips/kvm/tlb.c...
> error: while searching for:
> 	unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0;
> 	struct kvm *kvm = vcpu->kvm;
> 	pfn_t pfn0, pfn1;
> 	long tlb_lo[2];
> 
> 	tlb_lo[0] = tlb->tlb_lo0;
> 
> error: patch failed: arch/mips/kvm/tlb.c:361
> error: while searching for:
> 			VPN2_MASK & (PAGE_MASK << 1)))
> 		tlb_lo[(KVM_GUEST_COMMPAGE_ADDR >> PAGE_SHIFT) & 1] = 0;
> 
> 	if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[0])
> 				   >> PAGE_SHIFT) < 0)
> 		return -1;
> 
> 	if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[1])
> 				   >> PAGE_SHIFT) < 0)
> 		return -1;
> 
> 	pfn0 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[0])
> 				    >> PAGE_SHIFT];
> 	pfn1 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[1])
> 				    >> PAGE_SHIFT];
> 
> 	if (hpa0)
> 		*hpa0 = pfn0 << PAGE_SHIFT;
> 
> error: patch failed: arch/mips/kvm/tlb.c:374
> Applying patch arch/mips/kvm/tlb.c with 2 rejects...
> Rejected hunk #1.
> Rejected hunk #2.

This works for me (on 558ba5fd7d8d Linux 4.1.30) as long as 1/4 is
applied first. Are you applying them in the right order?

Cheers
James


[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]

[PATCH BACKPORT 3.17-4.4 3/4] MIPS: KVM: Fix gfn range check in kseg0 tlb faults

[James Hogan]

commit 0741f52d1b980dbeb290afe67d88fc2928edd8ab upstream.

Two consecutive gfns are loaded into host TLB, so ensure the range check
isn't off by one if guest_pmap_npages is odd.

Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[james.hogan@imgtec.com: Backport to v3.17.y - v4.4.y]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
---
 arch/mips/kvm/tlb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/kvm/tlb.c b/arch/mips/kvm/tlb.c
index 59e885fa4c65..836b61aabf86 100644
--- a/arch/mips/kvm/tlb.c
+++ b/arch/mips/kvm/tlb.c
@@ -276,7 +276,7 @@ int kvm_mips_handle_kseg0_tlb_fault(unsigned long badvaddr,
 	}
 
 	gfn = (KVM_GUEST_CPHYSADDR(badvaddr) >> PAGE_SHIFT);
-	if (gfn >= kvm->arch.guest_pmap_npages) {
+	if ((gfn | 1) >= kvm->arch.guest_pmap_npages) {
 		kvm_err("%s: Invalid gfn: %#llx, BadVaddr: %#lx\n", __func__,
 			gfn, badvaddr);
 		kvm_mips_dump_host_tlbs();
-- 
git-series 0.8.8

Patch "[PATCH BACKPORT 3.17-4.4 3/4] MIPS: KVM: Fix gfn range check in kseg0 tlb faults" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    [PATCH BACKPORT 3.17-4.4 3/4] MIPS: KVM: Fix gfn range check in kseg0 tlb faults

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mips-kvm-fix-gfn-range-check-in-kseg0-tlb-faults.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From james.hogan@imgtec.com  Thu Aug 18 11:44:51 2016
From: James Hogan <james.hogan@imgtec.com>
Date: Thu, 18 Aug 2016 10:05:31 +0100
Subject: [PATCH BACKPORT 3.17-4.4 3/4] MIPS: KVM: Fix gfn range check in kseg0 tlb faults
To: <stable@vger.kernel.org>
Cc: James Hogan <james.hogan@imgtec.com>, Paolo Bonzini <pbonzini@redhat.com>, Radim Krčmář <rkrcmar@redhat.com>, Ralf Baechle <ralf@linux-mips.org>, <linux-mips@linux-mips.org>, <kvm@vger.kernel.org>
Message-ID: <2c09ac935cd3721a0212d82eca7f9290481d5b4c.1471018436.git-series.james.hogan@imgtec.com>

From: James Hogan <james.hogan@imgtec.com>

commit 0741f52d1b980dbeb290afe67d88fc2928edd8ab upstream.

Two consecutive gfns are loaded into host TLB, so ensure the range check
isn't off by one if guest_pmap_npages is odd.

Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[james.hogan@imgtec.com: Backport to v3.17.y - v4.4.y]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/mips/kvm/tlb.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/mips/kvm/tlb.c
+++ b/arch/mips/kvm/tlb.c
@@ -276,7 +276,7 @@ int kvm_mips_handle_kseg0_tlb_fault(unsi
 	}
 
 	gfn = (KVM_GUEST_CPHYSADDR(badvaddr) >> PAGE_SHIFT);
-	if (gfn >= kvm->arch.guest_pmap_npages) {
+	if ((gfn | 1) >= kvm->arch.guest_pmap_npages) {
 		kvm_err("%s: Invalid gfn: %#llx, BadVaddr: %#lx\n", __func__,
 			gfn, badvaddr);
 		kvm_mips_dump_host_tlbs();


Patches currently in stable-queue which might be from james.hogan@imgtec.com are

queue-4.4/mips-kvm-add-missing-gfn-range-check.patch
queue-4.4/mips-kvm-propagate-kseg0-mapped-tlb-fault-errors.patch
queue-4.4/mips-kvm-fix-mapped-fault-broken-commpage-handling.patch
queue-4.4/mips-kvm-fix-gfn-range-check-in-kseg0-tlb-faults.patch

[PATCH BACKPORT 3.17-4.4 4/4] MIPS: KVM: Propagate kseg0/mapped tlb fault errors

[James Hogan]

commit 9b731bcfdec4c159ad2e4312e25d69221709b96a upstream.

Propagate errors from kvm_mips_handle_kseg0_tlb_fault() and
kvm_mips_handle_mapped_seg_tlb_fault(), usually triggering an internal
error since they normally indicate the guest accessed bad physical
memory or the commpage in an unexpected way.

Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.")
Fixes: e685c689f3a8 ("KVM/MIPS32: Privileged instruction/target branch emulation.")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[james.hogan@imgtec.com: Backport to v3.17.y - v4.4.y]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
---
 arch/mips/kvm/emulate.c | 40 ++++++++++++++++++++++++++++------------
 arch/mips/kvm/tlb.c     | 14 ++++++++++----
 2 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c
index dc10c77b7500..d6476d11212e 100644
--- a/arch/mips/kvm/emulate.c
+++ b/arch/mips/kvm/emulate.c
@@ -1629,8 +1629,14 @@ enum emulation_result kvm_mips_emulate_cache(uint32_t inst, uint32_t *opc,
 
 	preempt_disable();
 	if (KVM_GUEST_KSEGX(va) == KVM_GUEST_KSEG0) {
-		if (kvm_mips_host_tlb_lookup(vcpu, va) < 0)
-			kvm_mips_handle_kseg0_tlb_fault(va, vcpu);
+		if (kvm_mips_host_tlb_lookup(vcpu, va) < 0 &&
+		    kvm_mips_handle_kseg0_tlb_fault(va, vcpu)) {
+			kvm_err("%s: handling mapped kseg0 tlb fault for %lx, vcpu: %p, ASID: %#lx\n",
+				__func__, va, vcpu, read_c0_entryhi());
+			er = EMULATE_FAIL;
+			preempt_enable();
+			goto done;
+		}
 	} else if ((KVM_GUEST_KSEGX(va) < KVM_GUEST_KSEG0) ||
 		   KVM_GUEST_KSEGX(va) == KVM_GUEST_KSEG23) {
 		int index;
@@ -1665,14 +1671,19 @@ enum emulation_result kvm_mips_emulate_cache(uint32_t inst, uint32_t *opc,
 								run, vcpu);
 				preempt_enable();
 				goto dont_update_pc;
-			} else {
-				/*
-				 * We fault an entry from the guest tlb to the
-				 * shadow host TLB
-				 */
-				kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb,
-								     NULL,
-								     NULL);
+			}
+			/*
+			 * We fault an entry from the guest tlb to the
+			 * shadow host TLB
+			 */
+			if (kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb,
+								 NULL, NULL)) {
+				kvm_err("%s: handling mapped seg tlb fault for %lx, index: %u, vcpu: %p, ASID: %#lx\n",
+					__func__, va, index, vcpu,
+					read_c0_entryhi());
+				er = EMULATE_FAIL;
+				preempt_enable();
+				goto done;
 			}
 		}
 	} else {
@@ -2633,8 +2644,13 @@ enum emulation_result kvm_mips_handle_tlbmiss(unsigned long cause,
 			 * OK we have a Guest TLB entry, now inject it into the
 			 * shadow host TLB
 			 */
-			kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb, NULL,
-							     NULL);
+			if (kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb,
+								 NULL, NULL)) {
+				kvm_err("%s: handling mapped seg tlb fault for %lx, index: %u, vcpu: %p, ASID: %#lx\n",
+					__func__, va, index, vcpu,
+					read_c0_entryhi());
+				er = EMULATE_FAIL;
+			}
 		}
 	}
 
diff --git a/arch/mips/kvm/tlb.c b/arch/mips/kvm/tlb.c
index 836b61aabf86..7a7ed9ca01bb 100644
--- a/arch/mips/kvm/tlb.c
+++ b/arch/mips/kvm/tlb.c
@@ -808,10 +808,16 @@ uint32_t kvm_get_inst(uint32_t *opc, struct kvm_vcpu *vcpu)
 				local_irq_restore(flags);
 				return KVM_INVALID_INST;
 			}
-			kvm_mips_handle_mapped_seg_tlb_fault(vcpu,
-							     &vcpu->arch.
-							     guest_tlb[index],
-							     NULL, NULL);
+			if (kvm_mips_handle_mapped_seg_tlb_fault(vcpu,
+						&vcpu->arch.guest_tlb[index],
+						NULL, NULL)) {
+				kvm_err("%s: handling mapped seg tlb fault failed for %p, index: %u, vcpu: %p, ASID: %#lx\n",
+					__func__, opc, index, vcpu,
+					read_c0_entryhi());
+				kvm_mips_dump_guest_tlbs(vcpu);
+				local_irq_restore(flags);
+				return KVM_INVALID_INST;
+			}
 			inst = *(opc);
 		}
 		local_irq_restore(flags);
-- 
git-series 0.8.8

Patch "[PATCH BACKPORT 3.17-4.4 4/4] MIPS: KVM: Propagate kseg0/mapped tlb fault errors" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    [PATCH BACKPORT 3.17-4.4 4/4] MIPS: KVM: Propagate kseg0/mapped tlb fault errors

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mips-kvm-propagate-kseg0-mapped-tlb-fault-errors.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From james.hogan@imgtec.com  Thu Aug 18 11:45:02 2016
From: James Hogan <james.hogan@imgtec.com>
Date: Thu, 18 Aug 2016 10:05:32 +0100
Subject: [PATCH BACKPORT 3.17-4.4 4/4] MIPS: KVM: Propagate kseg0/mapped tlb fault errors
To: <stable@vger.kernel.org>
Cc: James Hogan <james.hogan@imgtec.com>, Paolo Bonzini <pbonzini@redhat.com>, Radim Krčmář <rkrcmar@redhat.com>, Ralf Baechle <ralf@linux-mips.org>, <linux-mips@linux-mips.org>, <kvm@vger.kernel.org>
Message-ID: <bc64b178eead8f261016756dc6d1348f4eba638c.1471018436.git-series.james.hogan@imgtec.com>

From: James Hogan <james.hogan@imgtec.com>

commit 9b731bcfdec4c159ad2e4312e25d69221709b96a upstream.

Propagate errors from kvm_mips_handle_kseg0_tlb_fault() and
kvm_mips_handle_mapped_seg_tlb_fault(), usually triggering an internal
error since they normally indicate the guest accessed bad physical
memory or the commpage in an unexpected way.

Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.")
Fixes: e685c689f3a8 ("KVM/MIPS32: Privileged instruction/target branch emulation.")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[james.hogan@imgtec.com: Backport to v3.17.y - v4.4.y]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/mips/kvm/emulate.c |   40 ++++++++++++++++++++++++++++------------
 arch/mips/kvm/tlb.c     |   14 ++++++++++----
 2 files changed, 38 insertions(+), 16 deletions(-)

--- a/arch/mips/kvm/emulate.c
+++ b/arch/mips/kvm/emulate.c
@@ -1629,8 +1629,14 @@ enum emulation_result kvm_mips_emulate_c
 
 	preempt_disable();
 	if (KVM_GUEST_KSEGX(va) == KVM_GUEST_KSEG0) {
-		if (kvm_mips_host_tlb_lookup(vcpu, va) < 0)
-			kvm_mips_handle_kseg0_tlb_fault(va, vcpu);
+		if (kvm_mips_host_tlb_lookup(vcpu, va) < 0 &&
+		    kvm_mips_handle_kseg0_tlb_fault(va, vcpu)) {
+			kvm_err("%s: handling mapped kseg0 tlb fault for %lx, vcpu: %p, ASID: %#lx\n",
+				__func__, va, vcpu, read_c0_entryhi());
+			er = EMULATE_FAIL;
+			preempt_enable();
+			goto done;
+		}
 	} else if ((KVM_GUEST_KSEGX(va) < KVM_GUEST_KSEG0) ||
 		   KVM_GUEST_KSEGX(va) == KVM_GUEST_KSEG23) {
 		int index;
@@ -1665,14 +1671,19 @@ enum emulation_result kvm_mips_emulate_c
 								run, vcpu);
 				preempt_enable();
 				goto dont_update_pc;
-			} else {
-				/*
-				 * We fault an entry from the guest tlb to the
-				 * shadow host TLB
-				 */
-				kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb,
-								     NULL,
-								     NULL);
+			}
+			/*
+			 * We fault an entry from the guest tlb to the
+			 * shadow host TLB
+			 */
+			if (kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb,
+								 NULL, NULL)) {
+				kvm_err("%s: handling mapped seg tlb fault for %lx, index: %u, vcpu: %p, ASID: %#lx\n",
+					__func__, va, index, vcpu,
+					read_c0_entryhi());
+				er = EMULATE_FAIL;
+				preempt_enable();
+				goto done;
 			}
 		}
 	} else {
@@ -2633,8 +2644,13 @@ enum emulation_result kvm_mips_handle_tl
 			 * OK we have a Guest TLB entry, now inject it into the
 			 * shadow host TLB
 			 */
-			kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb, NULL,
-							     NULL);
+			if (kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb,
+								 NULL, NULL)) {
+				kvm_err("%s: handling mapped seg tlb fault for %lx, index: %u, vcpu: %p, ASID: %#lx\n",
+					__func__, va, index, vcpu,
+					read_c0_entryhi());
+				er = EMULATE_FAIL;
+			}
 		}
 	}
 
--- a/arch/mips/kvm/tlb.c
+++ b/arch/mips/kvm/tlb.c
@@ -808,10 +808,16 @@ uint32_t kvm_get_inst(uint32_t *opc, str
 				local_irq_restore(flags);
 				return KVM_INVALID_INST;
 			}
-			kvm_mips_handle_mapped_seg_tlb_fault(vcpu,
-							     &vcpu->arch.
-							     guest_tlb[index],
-							     NULL, NULL);
+			if (kvm_mips_handle_mapped_seg_tlb_fault(vcpu,
+						&vcpu->arch.guest_tlb[index],
+						NULL, NULL)) {
+				kvm_err("%s: handling mapped seg tlb fault failed for %p, index: %u, vcpu: %p, ASID: %#lx\n",
+					__func__, opc, index, vcpu,
+					read_c0_entryhi());
+				kvm_mips_dump_guest_tlbs(vcpu);
+				local_irq_restore(flags);
+				return KVM_INVALID_INST;
+			}
 			inst = *(opc);
 		}
 		local_irq_restore(flags);


Patches currently in stable-queue which might be from james.hogan@imgtec.com are

queue-4.4/mips-kvm-add-missing-gfn-range-check.patch
queue-4.4/mips-kvm-propagate-kseg0-mapped-tlb-fault-errors.patch
queue-4.4/mips-kvm-fix-mapped-fault-broken-commpage-handling.patch
queue-4.4/mips-kvm-fix-gfn-range-check-in-kseg0-tlb-faults.patch

Re: [PATCH BACKPORT 3.17-4.4 0/4] MIPS: KVM: Fix MMU/TLB management issues

[Greg KH]

On Thu, Aug 18, 2016 at 10:05:28AM +0100, James Hogan wrote:
> These patches backport fixes for several issues in the management of
> MIPS KVM TLB faults to 4.4, and should apply back to 3.17 too.

All queued up for 4.4-stable, thanks.

greg k-h