linux-kernel - [PATCH 3.14 18/34] ARM/arm64: KVM: fix use of WnR bit in kvm_is_write

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Date:	Wed,  1 Jul 2015 11:40:25 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Laszlo Ersek <lersek@...hat.com>,
	Marc Zyngier <marc.zyngier@....com>,
	Christoffer Dall <christoffer.dall@...aro.org>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Shannon Zhao <shannon.zhao@...aro.org>
Subject: [PATCH 3.14 18/34] ARM/arm64: KVM: fix use of WnR bit in kvm_is_write_fault()

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ard Biesheuvel <ard.biesheuvel@...aro.org>

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 <lersek@...hat.com>
Acked-by: Marc Zyngier <marc.zyngier@....com>
Acked-by: Christoffer Dall <christoffer.dall@...aro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Shannon Zhao <shannon.zhao@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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(-)

--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -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));
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -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;
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -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) {}


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