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Patch "ARM/arm64: KVM: fix use of WnR bit in kvm_is_write_fault()" has been added to the 3.14-stable tree

PATCH [email protected] 1 participant 1 message Jul 1, 2015

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Stable branch Arm (32-bit) arm64 KVM arm64
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This is a note to let you know that I've just added the patch titled

ARM/arm64: KVM: fix use of WnR bit in kvm_is_write_fault()

to the 3.14-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:
arm-arm64-kvm-fix-use-of-wnr-bit-in-kvm_is_write_fault.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From a7d079cea2dffb112e26da2566dd84c0ef1fce97 Mon Sep 17 00:00:00 2001

From: Ard Biesheuvel <[email protected]>
Date: Tue, 9 Sep 2014 11:27:09 +0100
Subject: ARM/arm64: KVM: fix use of WnR bit in kvm_is_write_fault()

From: Ard Biesheuvel <[email protected]>

commit a7d079cea2dffb112e26da2566dd84c0ef1fce97 upstream.

[Since we don't backport commit 9804788 (arm/arm64: KVM: Support KVM_CAP_READONLY_MEM), ingore the changes in kvm_handle_guest_abort introduced by this patch.]

The ISS encoding for an exception from a Data Abort has a WnR bit[6] that indicates whether the Data Abort was caused by a read or a write instruction. While there are several fields in the encoding that are only valid if the ISV bit[24] is set, WnR is not one of them, so we can read it unconditionally.

Instead of fixing both implementations of kvm_is_write_fault() in place, reimplement it just once using kvm_vcpu_dabt_iswrite(), which already does the right thing with respect to the WnR bit. Also fix up the callers to pass 'vcpu'

Acked-by Laszlo Ersek <[email protected]>
Acked-by Marc Zyngier <[email protected]>
Acked-by Christoffer Dall <[email protected]>
Signed-off-by Ard Biesheuvel <[email protected]>
Signed-off-by Marc Zyngier <[email protected]>
Signed-off-by Shannon Zhao <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 arch/arm/include/asm/kvm_mmu.h   |   11 -----------
 arch/arm/kvm/mmu.c               |   10 +++++++++-
 arch/arm64/include/asm/kvm_mmu.h |   13 -------------
 3 files changed, 9 insertions(+), 25 deletions(-)
arch/arm/include/asm/kvm_mmu.h +0 -11
@@ -78,17 +78,6 @@ static inline void kvm_set_pte(pte_t *pt
 	flush_pmd_entry(pte);
 }
 
-static inline bool kvm_is_write_fault(unsigned long hsr)
-{
-	unsigned long hsr_ec = hsr >> HSR_EC_SHIFT;
-	if (hsr_ec == HSR_EC_IABT)
-		return false;
-	else if ((hsr & HSR_ISV) && !(hsr & HSR_WNR))
-		return false;
-	else
-		return true;
-}
-
 static inline void kvm_clean_pgd(pgd_t *pgd)
 {
 	clean_dcache_area(pgd, PTRS_PER_S2_PGD * sizeof(pgd_t));
arch/arm/kvm/mmu.c +9 -1
@@ -746,6 +746,14 @@ static bool transparent_hugepage_adjust(
 	return false;
 }
 
+static bool kvm_is_write_fault(struct kvm_vcpu *vcpu)
+{
+	if (kvm_vcpu_trap_is_iabt(vcpu))
+		return false;
+
+	return kvm_vcpu_dabt_iswrite(vcpu);
+}
+
 static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 			  struct kvm_memory_slot *memslot,
 			  unsigned long fault_status)

@@ -761,7 +769,7 @@ static int user_mem_abort(struct kvm_vcp
 	pfn_t pfn;
 	pgprot_t mem_type = PAGE_S2;
 
-	write_fault = kvm_is_write_fault(kvm_vcpu_get_hsr(vcpu));
+	write_fault = kvm_is_write_fault(vcpu);
 	if (fault_status == FSC_PERM && !write_fault) {
 		kvm_err("Unexpected L2 read permission error\n");
 		return -EFAULT;
arch/arm64/include/asm/kvm_mmu.h +0 -13
@@ -93,19 +93,6 @@ void kvm_clear_hyp_idmap(void);
 #define	kvm_set_pte(ptep, pte)		set_pte(ptep, pte)
 #define	kvm_set_pmd(pmdp, pmd)		set_pmd(pmdp, pmd)
 
-static inline bool kvm_is_write_fault(unsigned long esr)
-{
-	unsigned long esr_ec = esr >> ESR_EL2_EC_SHIFT;
-
-	if (esr_ec == ESR_EL2_EC_IABT)
-		return false;
-
-	if ((esr & ESR_EL2_ISV) && !(esr & ESR_EL2_WNR))
-		return false;
-
-	return true;
-}
-
 static inline void kvm_clean_pgd(pgd_t *pgd) {}
 static inline void kvm_clean_pmd_entry(pmd_t *pmd) {}
 static inline void kvm_clean_pte(pte_t *pte) {}

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/arm-arm64-kvm-fix-use-of-wnr-bit-in-kvm_is_write_fault.patch