[PATCH v5 11/13] RISC-V: KVM: add SBI extension reset callback

Clément Léger
2025-04-17T12:36:25Z

Currently, only the STA extension needed a reset function but that's
going to be the case for FWFT as well. Add a reset callback that can be
implemented by SBI extensions.

Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
arch/riscv/include/asm/kvm_host.h | 1 -
arch/riscv/include/asm/kvm_vcpu_sbi.h | 2 ++
arch/riscv/kvm/vcpu.c | 2 +-
arch/riscv/kvm/vcpu_sbi.c | 24 ++++++++++++++++++++++++
arch/riscv/kvm/vcpu_sbi_sta.c | 3 ++-
5 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 0e9c2fab6378..4fa02e082142 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -407,7 +407,6 @@ void __kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
bool kvm_riscv_vcpu_stopped(struct kvm_vcpu *vcpu);

-void kvm_riscv_vcpu_sbi_sta_reset(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_record_steal_time(struct kvm_vcpu *vcpu);

#endif /* __RISCV_KVM_HOST_H__ */
diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
index bcb90757b149..cb68b3a57c8f 100644
--- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
+++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
@@ -57,6 +57,7 @@ struct kvm_vcpu_sbi_extension {
*/
int (*init)(struct kvm_vcpu *vcpu);
void (*deinit)(struct kvm_vcpu *vcpu);
+ void (*reset)(struct kvm_vcpu *vcpu);
};

void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run);
@@ -78,6 +79,7 @@ bool riscv_vcpu_supports_sbi_ext(struct kvm_vcpu *vcpu, int idx);
int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run);
void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_sbi_deinit(struct kvm_vcpu *vcpu);
+void kvm_riscv_vcpu_sbi_reset(struct kvm_vcpu *vcpu);

int kvm_riscv_vcpu_get_reg_sbi_sta(struct kvm_vcpu *vcpu, unsigned long reg_num,
unsigned long *reg_val);
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 877bcc85c067..542747e2c7f5 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -94,7 +94,7 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
vcpu->arch.hfence_tail = 0;
memset(vcpu->arch.hfence_queue, 0, sizeof(vcpu->arch.hfence_queue));

- kvm_riscv_vcpu_sbi_sta_reset(vcpu);
+ kvm_riscv_vcpu_sbi_reset(vcpu);

/* Reset the guest CSRs for hotplug usecase */
if (loaded)
diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
index 3139f171c20f..50be079b5528 100644
--- a/arch/riscv/kvm/vcpu_sbi.c
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -536,3 +536,27 @@ void kvm_riscv_vcpu_sbi_deinit(struct kvm_vcpu *vcpu)
ext->deinit(vcpu);
}
}
+
+void kvm_riscv_vcpu_sbi_reset(struct kvm_vcpu *vcpu)
+{
+ struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
+ const struct kvm_riscv_sbi_extension_entry *entry;
+ const struct kvm_vcpu_sbi_extension *ext;
+ int idx, i;
+
+ for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
+ entry = &sbi_ext[i];
+ ext = entry->ext_ptr;
+ idx = entry->ext_idx;
+
+ if (idx < 0 || idx >= ARRAY_SIZE(scontext->ext_status))
+ continue;
+
+ if (scontext->ext_status[idx] != KVM_RISCV_SBI_EXT_STATUS_ENABLED ||
+ !ext->reset)
+ continue;
+
+ ext->reset(vcpu);
+ }
+}
+
diff --git a/arch/riscv/kvm/vcpu_sbi_sta.c b/arch/riscv/kvm/vcpu_sbi_sta.c
index 5f35427114c1..cc6cb7c8f0e4 100644
--- a/arch/riscv/kvm/vcpu_sbi_sta.c
+++ b/arch/riscv/kvm/vcpu_sbi_sta.c
@@ -16,7 +16,7 @@
#include <asm/sbi.h>
#include <asm/uaccess.h>

-void kvm_riscv_vcpu_sbi_sta_reset(struct kvm_vcpu *vcpu)
+static void kvm_riscv_vcpu_sbi_sta_reset(struct kvm_vcpu *vcpu)
{
vcpu->arch.sta.shmem = INVALID_GPA;
vcpu->arch.sta.last_steal = 0;
@@ -156,6 +156,7 @@ const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_sta = {
.extid_end = SBI_EXT_STA,
.handler = kvm_sbi_ext_sta_handler,
.probe = kvm_sbi_ext_sta_probe,
+ .reset = kvm_riscv_vcpu_sbi_sta_reset,
};

int kvm_riscv_vcpu_get_reg_sbi_sta(struct kvm_vcpu *vcpu,