RISCV: KVM: Add sstateen0 context save/restore

Define sstateen0 and add sstateen0 save/restore for guest VCPUs.
Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

arch/riscv/include/asm/csr.h

@@ -288,6 +288,7 @@
 #define CSR_STVEC		0x105
 #define CSR_SCOUNTEREN		0x106
 #define CSR_SENVCFG		0x10a
+#define CSR_SSTATEEN0		0x10c
 #define CSR_SSCRATCH		0x140
 #define CSR_SEPC		0x141
 #define CSR_SCAUSE		0x142

arch/riscv/include/asm/kvm_host.h

@@ -170,6 +170,10 @@ struct kvm_vcpu_config {
 	u64 hstateen0;
 };
 
+struct kvm_vcpu_smstateen_csr {
+	unsigned long sstateen0;
+};
+
 struct kvm_vcpu_arch {
 	/* VCPU ran at least once */
 	bool ran_atleast_once;
@@ -190,6 +194,7 @@ struct kvm_vcpu_arch {
 	unsigned long host_stvec;
 	unsigned long host_scounteren;
 	unsigned long host_senvcfg;
+	unsigned long host_sstateen0;
 
 	/* CPU context of Host */
 	struct kvm_cpu_context host_context;
@@ -200,6 +205,9 @@ struct kvm_vcpu_arch {
 	/* CPU CSR context of Guest VCPU */
 	struct kvm_vcpu_csr guest_csr;
 
+	/* CPU Smstateen CSR context of Guest VCPU */
+	struct kvm_vcpu_smstateen_csr smstateen_csr;
+
 	/* CPU context upon Guest VCPU reset */
 	struct kvm_cpu_context guest_reset_context;
 

arch/riscv/kvm/vcpu.c

@@ -621,16 +621,28 @@ static void kvm_riscv_update_hvip(struct kvm_vcpu *vcpu)
 
 static __always_inline void kvm_riscv_vcpu_swap_in_guest_state(struct kvm_vcpu *vcpu)
 {
+	struct kvm_vcpu_smstateen_csr *smcsr = &vcpu->arch.smstateen_csr;
 	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+	struct kvm_vcpu_config *cfg = &vcpu->arch.cfg;
 
 	vcpu->arch.host_senvcfg = csr_swap(CSR_SENVCFG, csr->senvcfg);
+	if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SMSTATEEN) &&
+	    (cfg->hstateen0 & SMSTATEEN0_SSTATEEN0))
+		vcpu->arch.host_sstateen0 = csr_swap(CSR_SSTATEEN0,
+						     smcsr->sstateen0);
 }
 
 static __always_inline void kvm_riscv_vcpu_swap_in_host_state(struct kvm_vcpu *vcpu)
 {
+	struct kvm_vcpu_smstateen_csr *smcsr = &vcpu->arch.smstateen_csr;
 	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+	struct kvm_vcpu_config *cfg = &vcpu->arch.cfg;
 
 	csr->senvcfg = csr_swap(CSR_SENVCFG, vcpu->arch.host_senvcfg);
+	if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SMSTATEEN) &&
+	    (cfg->hstateen0 & SMSTATEEN0_SSTATEEN0))
+		smcsr->sstateen0 = csr_swap(CSR_SSTATEEN0,
+					    vcpu->arch.host_sstateen0);
 }
 
 /*