[PATCH v3 3/7] RISC-V: KVM: Add kvm_vcpu_config

[Mayuresh Chitale]

Add a placeholder for all registers such as henvcfg, hstateen etc
which have 'static' configurations depending on extensions supported by
the guest. The values are derived once and are then subsequently written
to the corresponding CSRs while switching to the vcpu.

Signed-off-by: Mayuresh Chitale <mchitale at ventanamicro.com>
Reviewed-by: Andrew Jones <ajones at ventanamicro.com>
---
 arch/riscv/include/asm/kvm_host.h |  7 +++++++
 arch/riscv/kvm/vcpu.c             | 27 ++++++++++++++-------------
 2 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 2d8ee53b66c7..c0c50b4b3394 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -164,6 +164,10 @@ struct kvm_vcpu_csr {
 	unsigned long scounteren;
 };
 
+struct kvm_vcpu_config {
+	u64 henvcfg;
+};
+
 struct kvm_vcpu_arch {
 	/* VCPU ran at least once */
 	bool ran_atleast_once;
@@ -244,6 +248,9 @@ struct kvm_vcpu_arch {
 
 	/* Performance monitoring context */
 	struct kvm_pmu pmu_context;
+
+	/* 'static' configurations which are set only once */
+	struct kvm_vcpu_config cfg;
 };
 
 static inline void kvm_arch_sync_events(struct kvm *kvm) {}
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index d12ef99901fc..e01f47bb636f 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -980,31 +980,28 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 	return -EINVAL;
 }
 
-static void kvm_riscv_vcpu_update_config(const unsigned long *isa)
+static void kvm_riscv_vcpu_setup_config(struct kvm_vcpu *vcpu)
 {
-	u64 henvcfg = 0;
+	const unsigned long *isa = vcpu->arch.isa;
+	struct kvm_vcpu_config *cfg = &vcpu->arch.cfg;
 
 	if (riscv_isa_extension_available(isa, SVPBMT))
-		henvcfg |= ENVCFG_PBMTE;
+		cfg->henvcfg |= ENVCFG_PBMTE;
 
 	if (riscv_isa_extension_available(isa, SSTC))
-		henvcfg |= ENVCFG_STCE;
+		cfg->henvcfg |= ENVCFG_STCE;
 
 	if (riscv_isa_extension_available(isa, ZICBOM))
-		henvcfg |= (ENVCFG_CBIE | ENVCFG_CBCFE);
+		cfg->henvcfg |= (ENVCFG_CBIE | ENVCFG_CBCFE);
 
 	if (riscv_isa_extension_available(isa, ZICBOZ))
-		henvcfg |= ENVCFG_CBZE;
-
-	csr_write(CSR_HENVCFG, henvcfg);
-#ifdef CONFIG_32BIT
-	csr_write(CSR_HENVCFGH, henvcfg >> 32);
-#endif
+		cfg->henvcfg |= ENVCFG_CBZE;
 }
 
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
 	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+	struct kvm_vcpu_config *cfg = &vcpu->arch.cfg;
 
 	csr_write(CSR_VSSTATUS, csr->vsstatus);
 	csr_write(CSR_VSIE, csr->vsie);
@@ -1015,8 +1012,9 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	csr_write(CSR_VSTVAL, csr->vstval);
 	csr_write(CSR_HVIP, csr->hvip);
 	csr_write(CSR_VSATP, csr->vsatp);
-
-	kvm_riscv_vcpu_update_config(vcpu->arch.isa);
+	csr_write(CSR_HENVCFG, cfg->henvcfg);
+	if (IS_ENABLED(CONFIG_32BIT))
+		csr_write(CSR_HENVCFGH, cfg->henvcfg >> 32);
 
 	kvm_riscv_gstage_update_hgatp(vcpu);
 
@@ -1136,6 +1134,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 	struct kvm_cpu_trap trap;
 	struct kvm_run *run = vcpu->run;
 
+	if (!vcpu->arch.ran_atleast_once)
+		kvm_riscv_vcpu_setup_config(vcpu);
+
 	/* Mark this VCPU ran at least once */
 	vcpu->arch.ran_atleast_once = true;
 
-- 
2.34.1