ARM: KVM: Cleanup exception injection

David Binderman reported that the exception injection code had a
couple of unused variables lingering around.

Upon examination, it looked like this code could do with an
anticipated spring cleaning, which amounts to deduplicating
the CPSR/SPSR update, and making it look a bit more like
the architecture spec.

The spurious variables are removed in the process.

Reported-by: David Binderman <dcb314@hotmail.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 38 insertions, 36 deletions

diff --git a/arch/arm/kvm/emulate.c b/arch/arm/kvm/emulate.c
index d6c005283678..dc99159857b4 100644
--- a/arch/arm/kvm/emulate.c
+++ b/arch/arm/kvm/emulate.c
@@ -275,6 +275,40 @@ static u32 exc_vector_base(struct kvm_vcpu *vcpu)
                 return vbar;
 }
 
+/*
+ * Switch to an exception mode, updating both CPSR and SPSR. Follow
+ * the logic described in AArch32.EnterMode() from the ARMv8 ARM.
+ */
+static void kvm_update_psr(struct kvm_vcpu *vcpu, unsigned long mode)
+{
+        unsigned long cpsr = *vcpu_cpsr(vcpu);
+        u32 sctlr = vcpu->arch.cp15[c1_SCTLR];
+
+        *vcpu_cpsr(vcpu) = (cpsr & ~MODE_MASK) | mode;
+
+        switch (mode) {
+        case FIQ_MODE:
+                *vcpu_cpsr(vcpu) |= PSR_F_BIT;
+                /* Fall through */
+        case ABT_MODE:
+        case IRQ_MODE:
+                *vcpu_cpsr(vcpu) |= PSR_A_BIT;
+                /* Fall through */
+        default:
+                *vcpu_cpsr(vcpu) |= PSR_I_BIT;
+        }
+
+        *vcpu_cpsr(vcpu) &= ~(PSR_IT_MASK | PSR_J_BIT | PSR_E_BIT | PSR_T_BIT);
+
+        if (sctlr & SCTLR_TE)
+                *vcpu_cpsr(vcpu) |= PSR_T_BIT;
+        if (sctlr & SCTLR_EE)
+                *vcpu_cpsr(vcpu) |= PSR_E_BIT;
+
+        /* Note: These now point to the mode banked copies */
+        *vcpu_spsr(vcpu) = cpsr;
+}
+
 /**
  * kvm_inject_undefined - inject an undefined exception into the guest
  * @vcpu: The VCPU to receive the undefined exception
@@ -286,29 +320,13 @@ static u32 exc_vector_base(struct kvm_vcpu *vcpu)
  */
 void kvm_inject_undefined(struct kvm_vcpu *vcpu)
 {
-        unsigned long new_lr_value;
-        unsigned long new_spsr_value;
         unsigned long cpsr = *vcpu_cpsr(vcpu);
-        u32 sctlr = vcpu->arch.cp15[c1_SCTLR];
         bool is_thumb = (cpsr & PSR_T_BIT);
         u32 vect_offset = 4;
         u32 return_offset = (is_thumb) ? 2 : 4;
 
-        new_spsr_value = cpsr;
-        new_lr_value = *vcpu_pc(vcpu) - return_offset;
-
-        *vcpu_cpsr(vcpu) = (cpsr & ~MODE_MASK) | UND_MODE;
-        *vcpu_cpsr(vcpu) |= PSR_I_BIT;
-        *vcpu_cpsr(vcpu) &= ~(PSR_IT_MASK | PSR_J_BIT | PSR_E_BIT | PSR_T_BIT);
-
-        if (sctlr & SCTLR_TE)
-                *vcpu_cpsr(vcpu) |= PSR_T_BIT;
-        if (sctlr & SCTLR_EE)
-                *vcpu_cpsr(vcpu) |= PSR_E_BIT;
-
-        /* Note: These now point to UND banked copies */
-        *vcpu_spsr(vcpu) = cpsr;
-        *vcpu_reg(vcpu, 14) = new_lr_value;
+        kvm_update_psr(vcpu, UND_MODE);
+        *vcpu_reg(vcpu, 14) = *vcpu_pc(vcpu) - return_offset;
 
         /* Branch to exception vector */
         *vcpu_pc(vcpu) = exc_vector_base(vcpu) + vect_offset;
@@ -320,30 +338,14 @@ void kvm_inject_undefined(struct kvm_vcpu *vcpu)
  */
 static void inject_abt(struct kvm_vcpu *vcpu, bool is_pabt, unsigned long addr)
 {
-        unsigned long new_lr_value;
-        unsigned long new_spsr_value;
         unsigned long cpsr = *vcpu_cpsr(vcpu);
-        u32 sctlr = vcpu->arch.cp15[c1_SCTLR];
         bool is_thumb = (cpsr & PSR_T_BIT);
         u32 vect_offset;
         u32 return_offset = (is_thumb) ? 4 : 0;
         bool is_lpae;
 
-        new_spsr_value = cpsr;
-        new_lr_value = *vcpu_pc(vcpu) + return_offset;
-
-        *vcpu_cpsr(vcpu) = (cpsr & ~MODE_MASK) | ABT_MODE;
-        *vcpu_cpsr(vcpu) |= PSR_I_BIT | PSR_A_BIT;
-        *vcpu_cpsr(vcpu) &= ~(PSR_IT_MASK | PSR_J_BIT | PSR_E_BIT | PSR_T_BIT);
-
-        if (sctlr & SCTLR_TE)
-                *vcpu_cpsr(vcpu) |= PSR_T_BIT;
-        if (sctlr & SCTLR_EE)
-                *vcpu_cpsr(vcpu) |= PSR_E_BIT;
-
-        /* Note: These now point to ABT banked copies */
-        *vcpu_spsr(vcpu) = cpsr;
-        *vcpu_reg(vcpu, 14) = new_lr_value;
+        kvm_update_psr(vcpu, ABT_MODE);
+        *vcpu_reg(vcpu, 14) = *vcpu_pc(vcpu) + return_offset;
 
         if (is_pabt)
                 vect_offset = 12;