[PATCH v2 04/25] KVM: arm64: vgic-v3: Add hook to handle guest GICv3 sysreg accesses at EL2

Marc Zyngier
2017-06-01T10:20:56Z

In order to start handling guest access to GICv3 system registers,
let's add a hook that will get called when we trap a system register
access. This is gated by a new static key (vgic_v3_cpuif_trap).

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm64/include/asm/kvm_hyp.h | 1 +
arch/arm64/kvm/hyp/switch.c | 14 ++++++++++++++
include/kvm/arm_vgic.h | 1 +
virt/kvm/arm/hyp/vgic-v3-sr.c | 38 ++++++++++++++++++++++++++++++++++++++
virt/kvm/arm/vgic/vgic-v3.c | 2 ++
5 files changed, 56 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index b18e852d27e8..4572a9b560fa 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -127,6 +127,7 @@ int __vgic_v2_perform_cpuif_access(struct kvm_vcpu *vcpu);

void __vgic_v3_save_state(struct kvm_vcpu *vcpu);
void __vgic_v3_restore_state(struct kvm_vcpu *vcpu);
+int __vgic_v3_perform_cpuif_access(struct kvm_vcpu *vcpu);

void __timer_save_state(struct kvm_vcpu *vcpu);
void __timer_restore_state(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index aede1658aeda..dfd8ca16601b 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -350,6 +350,20 @@ int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
}
}

+ if (static_branch_unlikely(&vgic_v3_cpuif_trap) &&
+ exit_code == ARM_EXCEPTION_TRAP &&
+ (kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_SYS64 ||
+ kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_CP15_32)) {
+ int ret = __vgic_v3_perform_cpuif_access(vcpu);
+
+ if (ret == 1) {
+ __skip_instr(vcpu);
+ goto again;
+ }
+
+ /* 0 falls through to be handled out of EL2 */
+ }
+
fp_enabled = __fpsimd_enabled();

__sysreg_save_guest_state(guest_ctxt);
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index ef718586321c..39b9fc4dc65d 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -285,6 +285,7 @@ struct vgic_cpu {
};

extern struct static_key_false vgic_v2_cpuif_trap;
+extern struct static_key_false vgic_v3_cpuif_trap;

int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write);
void kvm_vgic_early_init(struct kvm *kvm);
diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c
index 990d9d1e85d0..943bf11252d9 100644
--- a/virt/kvm/arm/hyp/vgic-v3-sr.c
+++ b/virt/kvm/arm/hyp/vgic-v3-sr.c
@@ -19,6 +19,7 @@
#include <linux/irqchip/arm-gic-v3.h>
#include <linux/kvm_host.h>

+#include <asm/kvm_emulate.h>
#include <asm/kvm_hyp.h>

#define vtr_to_max_lr_idx(v) ((v) & 0xf)
@@ -371,3 +372,40 @@ void __hyp_text __vgic_v3_write_vmcr(u32 vmcr)
{
write_gicreg(vmcr, ICH_VMCR_EL2);
}
+
+#ifdef CONFIG_ARM64
+
+int __hyp_text __vgic_v3_perform_cpuif_access(struct kvm_vcpu *vcpu)
+{
+ int rt;
+ u32 esr;
+ u32 vmcr;
+ void (*fn)(struct kvm_vcpu *, u32, int);
+ bool is_read;
+ u32 sysreg;
+
+ esr = kvm_vcpu_get_hsr(vcpu);
+ if (vcpu_mode_is_32bit(vcpu)) {
+ if (!kvm_condition_valid(vcpu))
+ return 1;
+
+ sysreg = esr_cp15_to_sysreg(esr);
+ } else {
+ sysreg = esr_sys64_to_sysreg(esr);
+ }
+
+ is_read = (esr & ESR_ELx_SYS64_ISS_DIR_MASK) == ESR_ELx_SYS64_ISS_DIR_READ;
+
+ switch (sysreg) {
+ default:
+ return 0;
+ }
+
+ vmcr = __vgic_v3_read_vmcr();
+ rt = kvm_vcpu_sys_get_rt(vcpu);
+ fn(vcpu, vmcr, rt);
+
+ return 1;
+}
+
+#endif
diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index 6fe3f003636a..88d9bd9bf468 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -410,6 +410,8 @@ int vgic_v3_map_resources(struct kvm *kvm)
return ret;
}

+DEFINE_STATIC_KEY_FALSE(vgic_v3_cpuif_trap);
+
/**
* vgic_v3_probe - probe for a GICv3 compatible interrupt controller in DT
* @node: pointer to the DT node
--
2.11.0