linux-kernel - [PATCH 4.9 28/80] arm64: KVM: Fix decoding of Rt/Rt2 when trapping AArch32 CP accesses

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Date:   Thu, 18 May 2017 12:48:10 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Christoffer Dall <cdall@...aro.org>,
        Marc Zyngier <marc.zyngier@....com>
Subject: [PATCH 4.9 28/80] arm64: KVM: Fix decoding of Rt/Rt2 when trapping AArch32 CP accesses

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

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

From: Marc Zyngier <marc.zyngier@....com>

commit c667186f1c01ca8970c785888868b7ffd74e51ee upstream.

Our 32bit CP14/15 handling inherited some of the ARMv7 code for handling
the trapped system registers, completely missing the fact that the
fields for Rt and Rt2 are now 5 bit wide, and not 4...

Let's fix it, and provide an accessor for the most common Rt case.

Reviewed-by: Christoffer Dall <cdall@...aro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Christoffer Dall <cdall@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm64/include/asm/kvm_emulate.h |    6 ++++++
 arch/arm64/kvm/sys_regs.c            |    8 ++++----
 2 files changed, 10 insertions(+), 4 deletions(-)

--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -240,6 +240,12 @@ static inline u8 kvm_vcpu_trap_get_fault
 	return kvm_vcpu_get_hsr(vcpu) & ESR_ELx_FSC_TYPE;
 }
 
+static inline int kvm_vcpu_sys_get_rt(struct kvm_vcpu *vcpu)
+{
+	u32 esr = kvm_vcpu_get_hsr(vcpu);
+	return (esr & ESR_ELx_SYS64_ISS_RT_MASK) >> ESR_ELx_SYS64_ISS_RT_SHIFT;
+}
+
 static inline unsigned long kvm_vcpu_get_mpidr_aff(struct kvm_vcpu *vcpu)
 {
 	return vcpu_sys_reg(vcpu, MPIDR_EL1) & MPIDR_HWID_BITMASK;
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1573,8 +1573,8 @@ static int kvm_handle_cp_64(struct kvm_v
 {
 	struct sys_reg_params params;
 	u32 hsr = kvm_vcpu_get_hsr(vcpu);
-	int Rt = (hsr >> 5) & 0xf;
-	int Rt2 = (hsr >> 10) & 0xf;
+	int Rt = kvm_vcpu_sys_get_rt(vcpu);
+	int Rt2 = (hsr >> 10) & 0x1f;
 
 	params.is_aarch32 = true;
 	params.is_32bit = false;
@@ -1625,7 +1625,7 @@ static int kvm_handle_cp_32(struct kvm_v
 {
 	struct sys_reg_params params;
 	u32 hsr = kvm_vcpu_get_hsr(vcpu);
-	int Rt  = (hsr >> 5) & 0xf;
+	int Rt  = kvm_vcpu_sys_get_rt(vcpu);
 
 	params.is_aarch32 = true;
 	params.is_32bit = true;
@@ -1740,7 +1740,7 @@ int kvm_handle_sys_reg(struct kvm_vcpu *
 {
 	struct sys_reg_params params;
 	unsigned long esr = kvm_vcpu_get_hsr(vcpu);
-	int Rt = (esr >> 5) & 0x1f;
+	int Rt = kvm_vcpu_sys_get_rt(vcpu);
 	int ret;
 
 	trace_kvm_handle_sys_reg(esr);