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Tue, 30 Jun 2026 19:08:25 -0700 (PDT) From: Inochi Amaoto To: Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Anup Patel , Atish Patra , Paolo Bonzini , Shuah Khan , Thomas Huth , Sergey Matyukevich , Inochi Amaoto , Andy Chiu , Deepak Gupta Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-kselftest@vger.kernel.org, Yixun Lan , Longbin Li Subject: [PATCH v4 4/8] RISC-V: KVM: Add ssp context save/restore Date: Wed, 1 Jul 2026 10:07:41 +0800 Message-ID: <20260701020746.170157-5-inochiama@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260701020746.170157-1-inochiama@gmail.com> References: <20260701020746.170157-1-inochiama@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add ssp context save/restore for guest VCPUs and also add it to the ONE_REG interface to allow its access from user space. Signed-off-by: Inochi Amaoto --- arch/riscv/include/asm/kvm_host.h | 7 ++++ arch/riscv/include/uapi/asm/kvm.h | 8 ++++ arch/riscv/kvm/vcpu.c | 6 +++ arch/riscv/kvm/vcpu_onereg.c | 66 ++++++++++++++++++++++++++++++- 4 files changed, 85 insertions(+), 2 deletions(-) diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h index 60017ceec9d2..e5ed3b0e5a55 100644 --- a/arch/riscv/include/asm/kvm_host.h +++ b/arch/riscv/include/asm/kvm_host.h @@ -163,6 +163,10 @@ struct kvm_vcpu_smstateen_csr { unsigned long sstateen0; }; +struct kvm_vcpu_zicfiss_csr { + unsigned long ssp; +}; + struct kvm_vcpu_reset_state { spinlock_t lock; unsigned long pc; @@ -203,6 +207,9 @@ struct kvm_vcpu_arch { /* CPU Smstateen CSR context of Guest VCPU */ struct kvm_vcpu_smstateen_csr smstateen_csr; + /* CPU Zicfiss CSR context of Guest VCPU */ + struct kvm_vcpu_zicfiss_csr zicfiss_csr; + /* CPU reset state of Guest VCPU */ struct kvm_vcpu_reset_state reset_state; diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h index a27de850fa4c..fd4c81697617 100644 --- a/arch/riscv/include/uapi/asm/kvm.h +++ b/arch/riscv/include/uapi/asm/kvm.h @@ -102,6 +102,11 @@ struct kvm_riscv_smstateen_csr { unsigned long sstateen0; }; +/* Zicfiss CSR for KVM_GET_ONE_REG and KVM_SET_ONE_REG */ +struct kvm_riscv_zicfiss_csr { + unsigned long ssp; +}; + /* TIMER registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */ struct kvm_riscv_timer { __u64 frequency; @@ -266,12 +271,15 @@ struct kvm_riscv_sbi_fwft { #define KVM_REG_RISCV_CSR_GENERAL (0x0 << KVM_REG_RISCV_SUBTYPE_SHIFT) #define KVM_REG_RISCV_CSR_AIA (0x1 << KVM_REG_RISCV_SUBTYPE_SHIFT) #define KVM_REG_RISCV_CSR_SMSTATEEN (0x2 << KVM_REG_RISCV_SUBTYPE_SHIFT) +#define KVM_REG_RISCV_CSR_ZICFISS (0x3 << KVM_REG_RISCV_SUBTYPE_SHIFT) #define KVM_REG_RISCV_CSR_REG(name) \ (offsetof(struct kvm_riscv_csr, name) / sizeof(unsigned long)) #define KVM_REG_RISCV_CSR_AIA_REG(name) \ (offsetof(struct kvm_riscv_aia_csr, name) / sizeof(unsigned long)) #define KVM_REG_RISCV_CSR_SMSTATEEN_REG(name) \ (offsetof(struct kvm_riscv_smstateen_csr, name) / sizeof(unsigned long)) +#define KVM_REG_RISCV_CSR_ZICFISS_REG(name) \ + (offsetof(struct kvm_riscv_zicfiss_csr, name) / sizeof(unsigned long)) /* Timer registers are mapped as type 4 */ #define KVM_REG_RISCV_TIMER (0x04 << KVM_REG_RISCV_TYPE_SHIFT) diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c index cf6e231e76e2..1c2775a4834e 100644 --- a/arch/riscv/kvm/vcpu.c +++ b/arch/riscv/kvm/vcpu.c @@ -720,6 +720,7 @@ 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_zicfiss_csr *zicficsr = &vcpu->arch.zicfiss_csr; struct kvm_vcpu_smstateen_csr *smcsr = &vcpu->arch.smstateen_csr; struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr; @@ -727,10 +728,13 @@ static __always_inline void kvm_riscv_vcpu_swap_in_guest_state(struct kvm_vcpu * vcpu->arch.host_senvcfg = csr_swap(CSR_SENVCFG, csr->senvcfg); if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SMSTATEEN)) vcpu->arch.host_sstateen0 = csr_swap(CSR_SSTATEEN0, smcsr->sstateen0); + if (riscv_has_extension_unlikely(RISCV_ISA_EXT_ZICFISS)) + csr_write(CSR_SSP, zicficsr->ssp); } static __always_inline void kvm_riscv_vcpu_swap_in_host_state(struct kvm_vcpu *vcpu) { + struct kvm_vcpu_zicfiss_csr *zicficsr = &vcpu->arch.zicfiss_csr; struct kvm_vcpu_smstateen_csr *smcsr = &vcpu->arch.smstateen_csr; struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr; @@ -738,6 +742,8 @@ static __always_inline void kvm_riscv_vcpu_swap_in_host_state(struct kvm_vcpu *v csr->senvcfg = csr_swap(CSR_SENVCFG, vcpu->arch.host_senvcfg); if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SMSTATEEN)) smcsr->sstateen0 = csr_swap(CSR_SSTATEEN0, vcpu->arch.host_sstateen0); + if (riscv_has_extension_unlikely(RISCV_ISA_EXT_ZICFISS)) + zicficsr->ssp = csr_swap(CSR_SSP, 0); } /* diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c index bb920e8923c9..bd59aebc8b2e 100644 --- a/arch/riscv/kvm/vcpu_onereg.c +++ b/arch/riscv/kvm/vcpu_onereg.c @@ -355,6 +355,44 @@ static int kvm_riscv_vcpu_smstateen_get_csr(struct kvm_vcpu *vcpu, return 0; } +static inline int kvm_riscv_vcpu_zicfiss_set_csr(struct kvm_vcpu *vcpu, + unsigned long reg_num, + unsigned long reg_val) +{ + struct kvm_vcpu_zicfiss_csr *csr = &vcpu->arch.zicfiss_csr; + unsigned long regs_max = sizeof(struct kvm_vcpu_zicfiss_csr) / + sizeof(unsigned long); + + if (!riscv_isa_extension_available(vcpu->arch.isa, ZICFISS)) + return -ENOENT; + if (reg_num >= regs_max) + return -ENOENT; + + reg_num = array_index_nospec(reg_num, regs_max); + + ((unsigned long *)csr)[reg_num] = reg_val; + return 0; +} + +static int kvm_riscv_vcpu_zicfiss_get_csr(struct kvm_vcpu *vcpu, + unsigned long reg_num, + unsigned long *out_val) +{ + struct kvm_vcpu_zicfiss_csr *csr = &vcpu->arch.zicfiss_csr; + unsigned long regs_max = sizeof(struct kvm_vcpu_zicfiss_csr) / + sizeof(unsigned long); + + if (!riscv_isa_extension_available(vcpu->arch.isa, ZICFISS)) + return -ENOENT; + if (reg_num >= regs_max) + return -ENOENT; + + reg_num = array_index_nospec(reg_num, regs_max); + + *out_val = ((unsigned long *)csr)[reg_num]; + return 0; +} + static int kvm_riscv_vcpu_get_reg_csr(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) { @@ -381,6 +419,9 @@ static int kvm_riscv_vcpu_get_reg_csr(struct kvm_vcpu *vcpu, case KVM_REG_RISCV_CSR_SMSTATEEN: rc = kvm_riscv_vcpu_smstateen_get_csr(vcpu, reg_num, ®_val); break; + case KVM_REG_RISCV_CSR_ZICFISS: + rc = kvm_riscv_vcpu_zicfiss_get_csr(vcpu, reg_num, ®_val); + break; default: rc = -ENOENT; break; @@ -423,6 +464,9 @@ static int kvm_riscv_vcpu_set_reg_csr(struct kvm_vcpu *vcpu, case KVM_REG_RISCV_CSR_SMSTATEEN: rc = kvm_riscv_vcpu_smstateen_set_csr(vcpu, reg_num, reg_val); break; + case KVM_REG_RISCV_CSR_ZICFISS: + rc = kvm_riscv_vcpu_zicfiss_set_csr(vcpu, reg_num, reg_val); + break; default: rc = -ENOENT; break; @@ -688,7 +732,7 @@ static int copy_csr_reg_indices(const struct kvm_vcpu *vcpu, u64 __user *uindices) { int n1 = sizeof(struct kvm_riscv_csr) / sizeof(unsigned long); - int n2 = 0, n3 = 0; + int n2 = 0, n3 = 0, n4 = 0; /* copy general csr regs */ for (int i = 0; i < n1; i++) { @@ -740,7 +784,25 @@ static int copy_csr_reg_indices(const struct kvm_vcpu *vcpu, } } - return n1 + n2 + n3; + /* copy Zicfiss csr regs */ + if (riscv_isa_extension_available(vcpu->arch.isa, ZICFISS)) { + n4 = sizeof(struct kvm_riscv_zicfiss_csr) / sizeof(unsigned long); + + for (int i = 0; i < n4; i++) { + u64 size = IS_ENABLED(CONFIG_32BIT) ? + KVM_REG_SIZE_U32 : KVM_REG_SIZE_U64; + u64 reg = KVM_REG_RISCV | size | KVM_REG_RISCV_CSR | + KVM_REG_RISCV_CSR_ZICFISS | i; + + if (uindices) { + if (put_user(reg, uindices)) + return -EFAULT; + uindices++; + } + } + } + + return n1 + n2 + n3 + n4; } static inline unsigned long num_timer_regs(void) -- 2.55.0