KVM/riscv changes for 5.18

- Prevent KVM_COMPAT from being selected
 - Refine __kvm_riscv_switch_to() implementation
 - RISC-V SBI v0.3 support
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Merge tag 'kvm-riscv-5.18-1' of https://github.com/kvm-riscv/linux into HEAD

KVM/riscv changes for 5.18

- Prevent KVM_COMPAT from being selected
- Refine __kvm_riscv_switch_to() implementation
- RISC-V SBI v0.3 support

arch/riscv/include/asm/kvm_host.h

@@ -228,6 +228,7 @@ void kvm_riscv_stage2_vmid_update(struct kvm_vcpu *vcpu);
 
 void __kvm_riscv_unpriv_trap(void);
 
+void kvm_riscv_vcpu_wfi(struct kvm_vcpu *vcpu);
 unsigned long kvm_riscv_vcpu_unpriv_read(struct kvm_vcpu *vcpu,
 					 bool read_insn,
 					 unsigned long guest_addr,

arch/riscv/include/asm/kvm_vcpu_sbi.h

@@ -12,7 +12,7 @@
 #define KVM_SBI_IMPID 3
 
 #define KVM_SBI_VERSION_MAJOR 0
-#define KVM_SBI_VERSION_MINOR 2
+#define KVM_SBI_VERSION_MINOR 3
 
 struct kvm_vcpu_sbi_extension {
 	unsigned long extid_start;
@@ -28,6 +28,9 @@ struct kvm_vcpu_sbi_extension {
 };
 
 void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run);
+void kvm_riscv_vcpu_sbi_system_reset(struct kvm_vcpu *vcpu,
+				     struct kvm_run *run,
+				     u32 type, u64 flags);
 const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(unsigned long extid);
 
 #endif /* __RISCV_KVM_VCPU_SBI_H__ */

arch/riscv/include/asm/sbi.h

@@ -71,15 +71,32 @@ enum sbi_ext_hsm_fid {
 	SBI_EXT_HSM_HART_START = 0,
 	SBI_EXT_HSM_HART_STOP,
 	SBI_EXT_HSM_HART_STATUS,
+	SBI_EXT_HSM_HART_SUSPEND,
 };
 
-enum sbi_hsm_hart_status {
+enum sbi_hsm_hart_state {
-	SBI_HSM_HART_STATUS_STARTED = 0,
+	SBI_HSM_STATE_STARTED = 0,
-	SBI_HSM_HART_STATUS_STOPPED,
+	SBI_HSM_STATE_STOPPED,
-	SBI_HSM_HART_STATUS_START_PENDING,
+	SBI_HSM_STATE_START_PENDING,
-	SBI_HSM_HART_STATUS_STOP_PENDING,
+	SBI_HSM_STATE_STOP_PENDING,
+	SBI_HSM_STATE_SUSPENDED,
+	SBI_HSM_STATE_SUSPEND_PENDING,
+	SBI_HSM_STATE_RESUME_PENDING,
 };
 
+#define SBI_HSM_SUSP_BASE_MASK			0x7fffffff
+#define SBI_HSM_SUSP_NON_RET_BIT		0x80000000
+#define SBI_HSM_SUSP_PLAT_BASE			0x10000000
+
+#define SBI_HSM_SUSPEND_RET_DEFAULT		0x00000000
+#define SBI_HSM_SUSPEND_RET_PLATFORM		SBI_HSM_SUSP_PLAT_BASE
+#define SBI_HSM_SUSPEND_RET_LAST		SBI_HSM_SUSP_BASE_MASK
+#define SBI_HSM_SUSPEND_NON_RET_DEFAULT		SBI_HSM_SUSP_NON_RET_BIT
+#define SBI_HSM_SUSPEND_NON_RET_PLATFORM	(SBI_HSM_SUSP_NON_RET_BIT | \
+						 SBI_HSM_SUSP_PLAT_BASE)
+#define SBI_HSM_SUSPEND_NON_RET_LAST		(SBI_HSM_SUSP_NON_RET_BIT | \
+						 SBI_HSM_SUSP_BASE_MASK)
+
 enum sbi_ext_srst_fid {
 	SBI_EXT_SRST_RESET = 0,
 };

arch/riscv/kernel/cpu_ops_sbi.c

@@ -111,7 +111,7 @@ static int sbi_cpu_is_stopped(unsigned int cpuid)
 
 	rc = sbi_hsm_hart_get_status(hartid);
 
-	if (rc == SBI_HSM_HART_STATUS_STOPPED)
+	if (rc == SBI_HSM_STATE_STOPPED)
 		return 0;
 	return rc;
 }

arch/riscv/kvm/vcpu_exit.c

@@ -144,12 +144,7 @@ static int system_opcode_insn(struct kvm_vcpu *vcpu,
 {
 	if ((insn & INSN_MASK_WFI) == INSN_MATCH_WFI) {
 		vcpu->stat.wfi_exit_stat++;
-		if (!kvm_arch_vcpu_runnable(vcpu)) {
+		kvm_riscv_vcpu_wfi(vcpu);
-			srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
-			kvm_vcpu_halt(vcpu);
-			vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
-			kvm_clear_request(KVM_REQ_UNHALT, vcpu);
-		}
 		vcpu->arch.guest_context.sepc += INSN_LEN(insn);
 		return 1;
 	}
@@ -453,6 +448,21 @@ static int stage2_page_fault(struct kvm_vcpu *vcpu, struct kvm_run *run,
 	return 1;
 }
 
+/**
+ * kvm_riscv_vcpu_wfi -- Emulate wait for interrupt (WFI) behaviour
+ *
+ * @vcpu: The VCPU pointer
+ */
+void kvm_riscv_vcpu_wfi(struct kvm_vcpu *vcpu)
+{
+	if (!kvm_arch_vcpu_runnable(vcpu)) {
+		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+		kvm_vcpu_halt(vcpu);
+		vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+		kvm_clear_request(KVM_REQ_UNHALT, vcpu);
+	}
+}
+
 /**
  * kvm_riscv_vcpu_unpriv_read -- Read machine word from Guest memory
  *

arch/riscv/kvm/vcpu_sbi.c

@@ -45,6 +45,7 @@ extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_base;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_time;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_ipi;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_rfence;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_srst;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_experimental;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_vendor;
@@ -55,6 +56,7 @@ static const struct kvm_vcpu_sbi_extension *sbi_ext[] = {
 	&vcpu_sbi_ext_time,
 	&vcpu_sbi_ext_ipi,
 	&vcpu_sbi_ext_rfence,
+	&vcpu_sbi_ext_srst,
 	&vcpu_sbi_ext_hsm,
 	&vcpu_sbi_ext_experimental,
 	&vcpu_sbi_ext_vendor,
@@ -79,6 +81,23 @@ void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run)
 	run->riscv_sbi.ret[1] = cp->a1;
 }
 
+void kvm_riscv_vcpu_sbi_system_reset(struct kvm_vcpu *vcpu,
+				     struct kvm_run *run,
+				     u32 type, u64 flags)
+{
+	unsigned long i;
+	struct kvm_vcpu *tmp;
+
+	kvm_for_each_vcpu(i, tmp, vcpu->kvm)
+		tmp->arch.power_off = true;
+	kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_SLEEP);
+
+	memset(&run->system_event, 0, sizeof(run->system_event));
+	run->system_event.type = type;
+	run->system_event.flags = flags;
+	run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
+}
+
 int kvm_riscv_vcpu_sbi_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
 {
 	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;

arch/riscv/kvm/vcpu_sbi_hsm.c

@@ -60,9 +60,11 @@ static int kvm_sbi_hsm_vcpu_get_status(struct kvm_vcpu *vcpu)
 	if (!target_vcpu)
 		return -EINVAL;
 	if (!target_vcpu->arch.power_off)
-		return SBI_HSM_HART_STATUS_STARTED;
+		return SBI_HSM_STATE_STARTED;
+	else if (vcpu->stat.generic.blocking)
+		return SBI_HSM_STATE_SUSPENDED;
 	else
-		return SBI_HSM_HART_STATUS_STOPPED;
+		return SBI_HSM_STATE_STOPPED;
 }
 
 static int kvm_sbi_ext_hsm_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
@@ -91,6 +93,18 @@ static int kvm_sbi_ext_hsm_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
 			ret = 0;
 		}
 		break;
+	case SBI_EXT_HSM_HART_SUSPEND:
+		switch (cp->a0) {
+		case SBI_HSM_SUSPEND_RET_DEFAULT:
+			kvm_riscv_vcpu_wfi(vcpu);
+			break;
+		case SBI_HSM_SUSPEND_NON_RET_DEFAULT:
+			ret = -EOPNOTSUPP;
+			break;
+		default:
+			ret = -EINVAL;
+		}
+		break;
 	default:
 		ret = -EOPNOTSUPP;
 	}

arch/riscv/kvm/vcpu_sbi_replace.c

@@ -130,3 +130,47 @@ const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_rfence = {
 	.extid_end = SBI_EXT_RFENCE,
 	.handler = kvm_sbi_ext_rfence_handler,
 };
+
+static int kvm_sbi_ext_srst_handler(struct kvm_vcpu *vcpu,
+				    struct kvm_run *run,
+				    unsigned long *out_val,
+				    struct kvm_cpu_trap *utrap, bool *exit)
+{
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+	unsigned long funcid = cp->a6;
+	u32 reason = cp->a1;
+	u32 type = cp->a0;
+	int ret = 0;
+
+	switch (funcid) {
+	case SBI_EXT_SRST_RESET:
+		switch (type) {
+		case SBI_SRST_RESET_TYPE_SHUTDOWN:
+			kvm_riscv_vcpu_sbi_system_reset(vcpu, run,
+						KVM_SYSTEM_EVENT_SHUTDOWN,
+						reason);
+			*exit = true;
+			break;
+		case SBI_SRST_RESET_TYPE_COLD_REBOOT:
+		case SBI_SRST_RESET_TYPE_WARM_REBOOT:
+			kvm_riscv_vcpu_sbi_system_reset(vcpu, run,
+						KVM_SYSTEM_EVENT_RESET,
+						reason);
+			*exit = true;
+			break;
+		default:
+			ret = -EOPNOTSUPP;
+		}
+		break;
+	default:
+		ret = -EOPNOTSUPP;
+	}
+
+	return ret;
+}
+
+const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_srst = {
+	.extid_start = SBI_EXT_SRST,
+	.extid_end = SBI_EXT_SRST,
+	.handler = kvm_sbi_ext_srst_handler,
+};

arch/riscv/kvm/vcpu_sbi_v01.c

@@ -14,21 +14,6 @@
 #include <asm/kvm_vcpu_timer.h>
 #include <asm/kvm_vcpu_sbi.h>
 
-static void kvm_sbi_system_shutdown(struct kvm_vcpu *vcpu,
-				    struct kvm_run *run, u32 type)
-{
-	unsigned long i;
-	struct kvm_vcpu *tmp;
-
-	kvm_for_each_vcpu(i, tmp, vcpu->kvm)
-		tmp->arch.power_off = true;
-	kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_SLEEP);
-
-	memset(&run->system_event, 0, sizeof(run->system_event));
-	run->system_event.type = type;
-	run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
-}
-
 static int kvm_sbi_ext_v01_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
 				      unsigned long *out_val,
 				      struct kvm_cpu_trap *utrap,
@@ -80,7 +65,8 @@ static int kvm_sbi_ext_v01_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
 		}
 		break;
 	case SBI_EXT_0_1_SHUTDOWN:
-		kvm_sbi_system_shutdown(vcpu, run, KVM_SYSTEM_EVENT_SHUTDOWN);
+		kvm_riscv_vcpu_sbi_system_reset(vcpu, run,
+						KVM_SYSTEM_EVENT_SHUTDOWN, 0);
 		*exit = true;
 		break;
 	case SBI_EXT_0_1_REMOTE_FENCE_I:
@@ -111,7 +97,7 @@ static int kvm_sbi_ext_v01_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
 	default:
 		ret = -EINVAL;
 		break;
-	};
+	}
 
 	return ret;
 }

arch/riscv/kvm/vcpu_switch.S

@@ -41,33 +41,37 @@ ENTRY(__kvm_riscv_switch_to)
 	REG_S	s10, (KVM_ARCH_HOST_S10)(a0)
 	REG_S	s11, (KVM_ARCH_HOST_S11)(a0)
 
-	/* Save Host and Restore Guest SSTATUS */
+	/* Load Guest CSR values */
 	REG_L	t0, (KVM_ARCH_GUEST_SSTATUS)(a0)
+	REG_L	t1, (KVM_ARCH_GUEST_HSTATUS)(a0)
+	REG_L	t2, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
+	la	t4, __kvm_switch_return
+	REG_L	t5, (KVM_ARCH_GUEST_SEPC)(a0)
+
+	/* Save Host and Restore Guest SSTATUS */
 	csrrw	t0, CSR_SSTATUS, t0
-	REG_S	t0, (KVM_ARCH_HOST_SSTATUS)(a0)
 
 	/* Save Host and Restore Guest HSTATUS */
-	REG_L	t1, (KVM_ARCH_GUEST_HSTATUS)(a0)
 	csrrw	t1, CSR_HSTATUS, t1
-	REG_S	t1, (KVM_ARCH_HOST_HSTATUS)(a0)
 
 	/* Save Host and Restore Guest SCOUNTEREN */
-	REG_L	t2, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
 	csrrw	t2, CSR_SCOUNTEREN, t2
-	REG_S	t2, (KVM_ARCH_HOST_SCOUNTEREN)(a0)
+
+	/* Save Host STVEC and change it to return path */
+	csrrw	t4, CSR_STVEC, t4
 
 	/* Save Host SSCRATCH and change it to struct kvm_vcpu_arch pointer */
 	csrrw	t3, CSR_SSCRATCH, a0
-	REG_S	t3, (KVM_ARCH_HOST_SSCRATCH)(a0)
-
-	/* Save Host STVEC and change it to return path */
-	la	t4, __kvm_switch_return
-	csrrw	t4, CSR_STVEC, t4
-	REG_S	t4, (KVM_ARCH_HOST_STVEC)(a0)
 
 	/* Restore Guest SEPC */
-	REG_L	t0, (KVM_ARCH_GUEST_SEPC)(a0)
+	csrw	CSR_SEPC, t5
-	csrw	CSR_SEPC, t0
+
+	/* Store Host CSR values */
+	REG_S	t0, (KVM_ARCH_HOST_SSTATUS)(a0)
+	REG_S	t1, (KVM_ARCH_HOST_HSTATUS)(a0)
+	REG_S	t2, (KVM_ARCH_HOST_SCOUNTEREN)(a0)
+	REG_S	t3, (KVM_ARCH_HOST_SSCRATCH)(a0)
+	REG_S	t4, (KVM_ARCH_HOST_STVEC)(a0)
 
 	/* Restore Guest GPRs (except A0) */
 	REG_L	ra, (KVM_ARCH_GUEST_RA)(a0)
@@ -145,32 +149,36 @@ __kvm_switch_return:
 	REG_S	t5, (KVM_ARCH_GUEST_T5)(a0)
 	REG_S	t6, (KVM_ARCH_GUEST_T6)(a0)
 
+	/* Load Host CSR values */
+	REG_L	t1, (KVM_ARCH_HOST_STVEC)(a0)
+	REG_L	t2, (KVM_ARCH_HOST_SSCRATCH)(a0)
+	REG_L	t3, (KVM_ARCH_HOST_SCOUNTEREN)(a0)
+	REG_L	t4, (KVM_ARCH_HOST_HSTATUS)(a0)
+	REG_L	t5, (KVM_ARCH_HOST_SSTATUS)(a0)
+
 	/* Save Guest SEPC */
 	csrr	t0, CSR_SEPC
-	REG_S	t0, (KVM_ARCH_GUEST_SEPC)(a0)
-
-	/* Restore Host STVEC */
-	REG_L	t1, (KVM_ARCH_HOST_STVEC)(a0)
-	csrw	CSR_STVEC, t1
 
 	/* Save Guest A0 and Restore Host SSCRATCH */
-	REG_L	t2, (KVM_ARCH_HOST_SSCRATCH)(a0)
 	csrrw	t2, CSR_SSCRATCH, t2
-	REG_S	t2, (KVM_ARCH_GUEST_A0)(a0)
+
+	/* Restore Host STVEC */
+	csrw	CSR_STVEC, t1
 
 	/* Save Guest and Restore Host SCOUNTEREN */
-	REG_L	t3, (KVM_ARCH_HOST_SCOUNTEREN)(a0)
 	csrrw	t3, CSR_SCOUNTEREN, t3
-	REG_S	t3, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
 
 	/* Save Guest and Restore Host HSTATUS */
-	REG_L	t4, (KVM_ARCH_HOST_HSTATUS)(a0)
 	csrrw	t4, CSR_HSTATUS, t4
-	REG_S	t4, (KVM_ARCH_GUEST_HSTATUS)(a0)
 
 	/* Save Guest and Restore Host SSTATUS */
-	REG_L	t5, (KVM_ARCH_HOST_SSTATUS)(a0)
 	csrrw	t5, CSR_SSTATUS, t5
+
+	/* Store Guest CSR values */
+	REG_S	t0, (KVM_ARCH_GUEST_SEPC)(a0)
+	REG_S	t2, (KVM_ARCH_GUEST_A0)(a0)
+	REG_S	t3, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
+	REG_S	t4, (KVM_ARCH_GUEST_HSTATUS)(a0)
 	REG_S	t5, (KVM_ARCH_GUEST_SSTATUS)(a0)
 
 	/* Restore Host GPRs (except A0 and T0-T6) */

virt/kvm/Kconfig

@@ -53,7 +53,7 @@ config KVM_GENERIC_DIRTYLOG_READ_PROTECT
 
 config KVM_COMPAT
        def_bool y
-       depends on KVM && COMPAT && !(S390 || ARM64)
+       depends on KVM && COMPAT && !(S390 || ARM64 || RISCV)
 
 config HAVE_KVM_IRQ_BYPASS
        bool