[PATCH 23/59] KVM: arm64: nv: Respect virtual HCR_EL2.TWX setting

Marc Zyngier
2019-06-21T09:39:54Z

From: Jintack Lim <jintack.lim@linaro.org>

Forward exceptions due to WFI or WFE instructions to the virtual EL2 if
they are not coming from the virtual EL2 and virtual HCR_EL2.TWX is set.

Signed-off-by: Jintack Lim <jintack.lim@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm64/include/asm/kvm_nested.h | 2 ++
arch/arm64/kvm/Makefile | 1 +
arch/arm64/kvm/handle_exit.c | 13 +++++++++-
arch/arm64/kvm/nested.c | 39 +++++++++++++++++++++++++++++
4 files changed, 54 insertions(+), 1 deletion(-)
create mode 100644 arch/arm64/kvm/nested.c

diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
index 8a3d121a0b42..645e5e11b749 100644
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -10,4 +10,6 @@ static inline bool nested_virt_in_use(const struct kvm_vcpu *vcpu)
test_bit(KVM_ARM_VCPU_NESTED_VIRT, vcpu->arch.features);
}

+int handle_wfx_nested(struct kvm_vcpu *vcpu, bool is_wfe);
+
#endif /* __ARM64_KVM_NESTED_H */
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 9e450aea7db6..f11bd8b0d837 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -36,4 +36,5 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/irqchip.o
kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/arch_timer.o
kvm-$(CONFIG_KVM_ARM_PMU) += $(KVM)/arm/pmu.o

+kvm-$(CONFIG_KVM_ARM_HOST) += nested.o
kvm-$(CONFIG_KVM_ARM_HOST) += emulate-nested.o
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index e348c15c81bc..ddba212fd6ec 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -127,7 +127,18 @@ static int handle_no_fpsimd(struct kvm_vcpu *vcpu, struct kvm_run *run)
*/
static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
- if (kvm_vcpu_get_hsr(vcpu) & ESR_ELx_WFx_ISS_WFE) {
+ bool is_wfe = !!(kvm_vcpu_get_hsr(vcpu) & ESR_ELx_WFx_ISS_WFE);
+
+ if (nested_virt_in_use(vcpu)) {
+ int ret = handle_wfx_nested(vcpu, is_wfe);
+
+ if (ret < 0 && ret != -EINVAL)
+ return ret;
+ else if (ret >= 0)
+ return ret;
+ }
+
+ if (is_wfe) {
trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true);
vcpu->stat.wfe_exit_stat++;
kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
new file mode 100644
index 000000000000..3872e3cf1691
--- /dev/null
+++ b/arch/arm64/kvm/nested.c
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2017 - Columbia University and Linaro Ltd.
+ * Author: Jintack Lim <jintack.lim@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/kvm.h>
+#include <linux/kvm_host.h>
+
+#include <asm/kvm_emulate.h>
+
+/*
+ * Inject wfx to the virtual EL2 if this is not from the virtual EL2 and
+ * the virtual HCR_EL2.TWX is set. Otherwise, let the host hypervisor
+ * handle this.
+ */
+int handle_wfx_nested(struct kvm_vcpu *vcpu, bool is_wfe)
+{
+ u64 hcr_el2 = __vcpu_sys_reg(vcpu, HCR_EL2);
+
+ if (vcpu_mode_el2(vcpu))
+ return -EINVAL;
+
+ if ((is_wfe && (hcr_el2 & HCR_TWE)) || (!is_wfe && (hcr_el2 & HCR_TWI)))
+ return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
+
+ return -EINVAL;
+}
--
2.20.1