For ARM host like Realview-PB-A8 the linux guest kernel generates alignment faults at boot time and crashes.
To handle this situation without adding much overhead we emulate SCTLR & CPACR read/write and ignore operations SCTLR_A bit.
With this patch in-place we can boot Linux on Realview-PB-A8 guest.
Signed-off-by: Anup Patel <anup at brainfault.org>
---
arch/arm/kvm/emulate.c | 42 ++++++++++++++++++++++++++++++++++++++++++
arch/arm/kvm/interrupts.S | 4 ++--
2 files changed, 44 insertions(+), 2 deletions(-)
diff --git a/arch/arm/kvm/emulate.c b/arch/arm/kvm/emulate.c
index e356d1c..8a69d49 100644
--- a/arch/arm/kvm/emulate.c
+++ b/arch/arm/kvm/emulate.c
@@ -223,6 +223,38 @@ static bool read_zero(struct kvm_vcpu *vcpu,
return true;
}
+static bool write_sctlr(struct kvm_vcpu *vcpu,
+ const struct coproc_params *p,
+ unsigned long arg)
+{
+ vcpu->arch.cp15[c1_SCTLR] = *vcpu_reg(vcpu, p->Rt1) & ~0x00000002;
+ return true;
+}
+
+static bool read_sctlr(struct kvm_vcpu *vcpu,
+ const struct coproc_params *p,
+ unsigned long arg)
+{
+ *vcpu_reg(vcpu, p->Rt1) = vcpu->arch.cp15[c1_SCTLR];
+ return true;
+}
+
+static bool write_cpacr(struct kvm_vcpu *vcpu,
+ const struct coproc_params *p,
+ unsigned long arg)
+{
+ vcpu->arch.cp15[c1_CPACR] = *vcpu_reg(vcpu, p->Rt1);
+ return true;
+}
+
+static bool read_cpacr(struct kvm_vcpu *vcpu,
+ const struct coproc_params *p,
+ unsigned long arg)
+{
+ *vcpu_reg(vcpu, p->Rt1) = vcpu->arch.cp15[c1_CPACR];
+ return true;
+}
+
static bool read_l2ctlr(struct kvm_vcpu *vcpu,
const struct coproc_params *p,
unsigned long arg)
@@ -278,6 +310,16 @@ struct coproc_emulate {
static const struct coproc_emulate coproc_emulate[] = {
/*
+ * SCTLR access:
+ */
+ { CRn( 1), CRm( 0), Op1( 0), Op2( 0), is32, WRITE, write_sctlr},
+ { CRn( 1), CRm( 0), Op1( 0), Op2( 0), is32, READ, read_sctlr},
+ /*
+ * CPACR access:
+ */
+ { CRn( 1), CRm( 0), Op1( 0), Op2( 2), is32, WRITE, write_cpacr},
+ { CRn( 1), CRm( 0), Op1( 0), Op2( 2), is32, READ, read_cpacr},
+ /*
* L2CTLR access:
*
* Ignore writes completely.
diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S
index 0cf4965..942667a 100644
--- a/arch/arm/kvm/interrupts.S
+++ b/arch/arm/kvm/interrupts.S
@@ -240,9 +240,9 @@ ENTRY(__kvm_flush_vm_context)
* (hardware reset value is 0) */
.macro set_hstr entry
mrc p15, 4, r2, c1, c1, 3
- ldr r3, =0x9e00
+ ldr r3, =0x9e02
.if \entry == 1
- orr r2, r2, r3 @ Trap CR{9,10,11,12,15}
+ orr r2, r2, r3 @ Trap CR{1,9,10,11,12,15}
.else
bic r2, r2, r3 @ Don't trap any CRx accesses
.endif
--
1.7.0.4
