[PATCH v2 07/16] KVM: arm64: Wire MMIO guard hypercalls

[Marc Zyngier]

Plumb in the hypercall interface to allow a guest to discover,
enroll, map and unmap MMIO regions.

Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/kvm/hypercalls.c | 28 ++++++++++++++++++++++++++++
 include/linux/arm-smccc.h   | 28 ++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 30da78f72b3b..c39aab55ecae 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -5,6 +5,7 @@
 #include <linux/kvm_host.h>
 
 #include <asm/kvm_emulate.h>
+#include <asm/kvm_mmu.h>
 
 #include <kvm/arm_hypercalls.h>
 #include <kvm/arm_psci.h>
@@ -129,10 +130,37 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
 		val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES);
 		val[0] |= BIT(ARM_SMCCC_KVM_FUNC_PTP);
+		/* Only advertise MMIO guard to 64bit guests */
+		if (!vcpu_mode_is_32bit(vcpu)) {
+			val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MMIO_GUARD_INFO);
+			val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MMIO_GUARD_ENROLL);
+			val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MMIO_GUARD_MAP);
+			val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MMIO_GUARD_UNMAP);
+		}
 		break;
 	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
 		kvm_ptp_get_time(vcpu, val);
 		break;
+	case ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_INFO_FUNC_ID:
+		if (!vcpu_mode_is_32bit(vcpu))
+			val[0] = PAGE_SIZE;
+		break;
+	case ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_ENROLL_FUNC_ID:
+		if (!vcpu_mode_is_32bit(vcpu)) {
+			set_bit(KVM_ARCH_FLAG_MMIO_GUARD, &vcpu->kvm->arch.flags);
+			val[0] = SMCCC_RET_SUCCESS;
+		}
+		break;
+	case ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_MAP_FUNC_ID:
+		if (!vcpu_mode_is_32bit(vcpu) &&
+		    kvm_install_ioguard_page(vcpu, vcpu_get_reg(vcpu, 1)))
+			val[0] = SMCCC_RET_SUCCESS;
+		break;
+	case ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_UNMAP_FUNC_ID:
+		if (!vcpu_mode_is_32bit(vcpu) &&
+		    kvm_remove_ioguard_page(vcpu, vcpu_get_reg(vcpu, 1)))
+			val[0] = SMCCC_RET_SUCCESS;
+		break;
 	case ARM_SMCCC_TRNG_VERSION:
 	case ARM_SMCCC_TRNG_FEATURES:
 	case ARM_SMCCC_TRNG_GET_UUID:
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index 7d1cabe15262..4aab2078d8d3 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -107,6 +107,10 @@
 /* KVM "vendor specific" services */
 #define ARM_SMCCC_KVM_FUNC_FEATURES		0
 #define ARM_SMCCC_KVM_FUNC_PTP			1
+#define ARM_SMCCC_KVM_FUNC_MMIO_GUARD_INFO	2
+#define ARM_SMCCC_KVM_FUNC_MMIO_GUARD_ENROLL	3
+#define ARM_SMCCC_KVM_FUNC_MMIO_GUARD_MAP	4
+#define ARM_SMCCC_KVM_FUNC_MMIO_GUARD_UNMAP	5
 #define ARM_SMCCC_KVM_FUNC_FEATURES_2		127
 #define ARM_SMCCC_KVM_NUM_FUNCS			128
 
@@ -133,6 +137,30 @@
 #define KVM_PTP_VIRT_COUNTER			0
 #define KVM_PTP_PHYS_COUNTER			1
 
+#define ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_INFO_FUNC_ID		\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_64,				\
+			   ARM_SMCCC_OWNER_VENDOR_HYP,			\
+			   ARM_SMCCC_KVM_FUNC_MMIO_GUARD_INFO)
+
+#define ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_ENROLL_FUNC_ID		\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_64,				\
+			   ARM_SMCCC_OWNER_VENDOR_HYP,			\
+			   ARM_SMCCC_KVM_FUNC_MMIO_GUARD_ENROLL)
+
+#define ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_MAP_FUNC_ID			\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_64,				\
+			   ARM_SMCCC_OWNER_VENDOR_HYP,			\
+			   ARM_SMCCC_KVM_FUNC_MMIO_GUARD_MAP)
+
+#define ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_UNMAP_FUNC_ID		\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_64,				\
+			   ARM_SMCCC_OWNER_VENDOR_HYP,			\
+			   ARM_SMCCC_KVM_FUNC_MMIO_GUARD_UNMAP)
+
 /* Paravirtualised time calls (defined by ARM DEN0057A) */
 #define ARM_SMCCC_HV_PV_TIME_FEATURES				\
 	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
-- 
2.30.2