ARM: KVM: add world-switch for AMAIR{0,1}

commit af20814e upstream.

HCR.TVM traps (among other things) accesses to AMAIR0 and AMAIR1.
In order to minimise the amount of surprise a guest could generate by
trying to access these registers with caches off, add them to the
list of registers we switch/handle.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

arch/arm/include/asm/kvm_asm.h

@@ -48,7 +48,9 @@
 #define c13_TID_URO	26	/* Thread ID, User R/O */
 #define c13_TID_PRIV	27	/* Thread ID, Privileged */
 #define c14_CNTKCTL	28	/* Timer Control Register (PL1) */
-#define NR_CP15_REGS	29	/* Number of regs (incl. invalid) */
+#define c10_AMAIR0	29	/* Auxilary Memory Attribute Indirection Reg0 */
+#define c10_AMAIR1	30	/* Auxilary Memory Attribute Indirection Reg1 */
+#define NR_CP15_REGS	31	/* Number of regs (incl. invalid) */
 
 #define ARM_EXCEPTION_RESET	  0
 #define ARM_EXCEPTION_UNDEFINED   1

arch/arm/kvm/coproc.c

@@ -112,6 +112,23 @@ static bool access_dcsw(struct kvm_vcpu *vcpu,
 	return true;
 }
 
+/*
+ * Generic accessor for VM registers. Only called as long as HCR_TVM
+ * is set.
+ */
+static bool access_vm_reg(struct kvm_vcpu *vcpu,
+			 const struct coproc_params *p,
+			 const struct coproc_reg *r)
+{
+	BUG_ON(!p->is_write);
+
+	vcpu->arch.cp15[r->reg] = *vcpu_reg(vcpu, p->Rt1);
+	if (p->is_64bit)
+		vcpu->arch.cp15[r->reg + 1] = *vcpu_reg(vcpu, p->Rt2);
+
+	return true;
+}
+
 /*
  * We could trap ID_DFR0 and tell the guest we don't support performance
  * monitoring.  Unfortunately the patch to make the kernel check ID_DFR0 was
@@ -217,6 +234,12 @@ static const struct coproc_reg cp15_regs[] = {
 	{ CRn(10), CRm( 2), Op1( 0), Op2( 1), is32,
 			NULL, reset_unknown, c10_NMRR},
 
+	/* AMAIR0/AMAIR1: swapped by interrupt.S. */
+	{ CRn(10), CRm( 3), Op1( 0), Op2( 0), is32,
+			access_vm_reg, reset_unknown, c10_AMAIR0},
+	{ CRn(10), CRm( 3), Op1( 0), Op2( 1), is32,
+			access_vm_reg, reset_unknown, c10_AMAIR1},
+
 	/* VBAR: swapped by interrupt.S. */
 	{ CRn(12), CRm( 0), Op1( 0), Op2( 0), is32,
 			NULL, reset_val, c12_VBAR, 0x00000000 },

arch/arm/kvm/interrupts_head.S

@@ -303,13 +303,17 @@ vcpu	.req	r0		@ vcpu pointer always in r0
 
 	mrc	p15, 0, r2, c14, c1, 0	@ CNTKCTL
 	mrrc	p15, 0, r4, r5, c7	@ PAR
+	mrc	p15, 0, r6, c10, c3, 0	@ AMAIR0
+	mrc	p15, 0, r7, c10, c3, 1	@ AMAIR1
 
 	.if \store_to_vcpu == 0
-	push	{r2,r4-r5}
+	push	{r2,r4-r7}
 	.else
 	str	r2, [vcpu, #CP15_OFFSET(c14_CNTKCTL)]
 	add	r12, vcpu, #CP15_OFFSET(c7_PAR)
 	strd	r4, r5, [r12]
+	str	r6, [vcpu, #CP15_OFFSET(c10_AMAIR0)]
+	str	r7, [vcpu, #CP15_OFFSET(c10_AMAIR1)]
 	.endif
 .endm
 
@@ -322,15 +326,19 @@ vcpu	.req	r0		@ vcpu pointer always in r0
  */
 .macro write_cp15_state read_from_vcpu
 	.if \read_from_vcpu == 0
-	pop	{r2,r4-r5}
+	pop	{r2,r4-r7}
 	.else
 	ldr	r2, [vcpu, #CP15_OFFSET(c14_CNTKCTL)]
 	add	r12, vcpu, #CP15_OFFSET(c7_PAR)
 	ldrd	r4, r5, [r12]
+	ldr	r6, [vcpu, #CP15_OFFSET(c10_AMAIR0)]
+	ldr	r7, [vcpu, #CP15_OFFSET(c10_AMAIR1)]
 	.endif
 
 	mcr	p15, 0, r2, c14, c1, 0	@ CNTKCTL
 	mcrr	p15, 0, r4, r5, c7	@ PAR
+	mcr	p15, 0, r6, c10, c3, 0	@ AMAIR0
+	mcr	p15, 0, r7, c10, c3, 1	@ AMAIR1
 
 	.if \read_from_vcpu == 0
 	pop	{r2-r12}