[PATCH v3 22/66] KVM: arm64: nv: Respect virtual HCR_EL2.TWX setting

[Marc Zyngier]

From: Jintack Lim <jintack.lim at 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 at linaro.org>
Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/include/asm/kvm_nested.h |  2 ++
 arch/arm64/kvm/Makefile             |  2 +-
 arch/arm64/kvm/handle_exit.c        | 11 +++++++-
 arch/arm64/kvm/nested.c             | 40 +++++++++++++++++++++++++++++
 4 files changed, 53 insertions(+), 2 deletions(-)
 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 67a2c0d05233..4c2ac9650a3e 100644
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -61,4 +61,6 @@ static inline u64 translate_cnthctl_el2_to_cntkctl_el1(u64 cnthctl)
 		(cnthctl & (CNTHCTL_EVNTI | CNTHCTL_EVNTDIR | CNTHCTL_EVNTEN)));
 }
 
+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 672acdf1e993..7bb1d1314cad 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -17,7 +17,7 @@ kvm-y := $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o \
 	 guest.o debug.o reset.o sys_regs.o \
 	 vgic-sys-reg-v3.o fpsimd.o pmu.o \
 	 arch_timer.o \
-	 emulate-nested.o \
+	 emulate-nested.o nested.o \
 	 vgic/vgic.o vgic/vgic-init.o \
 	 vgic/vgic-irqfd.o vgic/vgic-v2.o \
 	 vgic/vgic-v3.o vgic/vgic-v4.o \
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index fe1dc0551991..a2437b2380f1 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -119,7 +119,16 @@ static int handle_no_fpsimd(struct kvm_vcpu *vcpu)
  */
 static int kvm_handle_wfx(struct kvm_vcpu *vcpu)
 {
-	if (kvm_vcpu_get_esr(vcpu) & ESR_ELx_WFx_ISS_WFE) {
+	bool is_wfe = !!(kvm_vcpu_get_esr(vcpu) & ESR_ELx_WFx_ISS_WFE);
+
+	if (nested_virt_in_use(vcpu)) {
+		int ret = handle_wfx_nested(vcpu, is_wfe);
+
+		if (ret != -EINVAL)
+			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..42a96c8d2adc
--- /dev/null
+++ b/arch/arm64/kvm/nested.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017 - Columbia University and Linaro Ltd.
+ * Author: Jintack Lim <jintack.lim at 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_esr(vcpu));
+
+	return -EINVAL;
+}
-- 
2.29.2