Re: [PATCH v5 13/13] RISC-V: KVM: add support for SBI_FWFT_MISALIGNED_DELEG

On 24/04/2025 13:34, Andrew Jones wrote:

On Thu, Apr 17, 2025 at 02:20:00PM +0200, Clément Léger wrote:

...

SBI_FWFT_MISALIGNED_DELEG needs hedeleg to be modified to delegate misaligned load/store exceptions. Save and restore it during CPU load/put.

Signed-off-by: Clément Léger cleger@rivosinc.com Reviewed-by: Deepak Gupta debug@rivosinc.com Reviewed-by: Andrew Jones ajones@ventanamicro.com

---

arch/riscv/kvm/vcpu.c | 3 +++ arch/riscv/kvm/vcpu_sbi_fwft.c | 36 ++++++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+)

diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c index 542747e2c7f5..d98e379945c3 100644 --- a/arch/riscv/kvm/vcpu.c +++ b/arch/riscv/kvm/vcpu.c @@ -646,6 +646,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) { void *nsh; struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;

• struct kvm_vcpu_config *cfg = &vcpu->arch.cfg;

vcpu->cpu = -1; @@ -671,6 +672,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) csr->vstval = nacl_csr_read(nsh, CSR_VSTVAL); csr->hvip = nacl_csr_read(nsh, CSR_HVIP); csr->vsatp = nacl_csr_read(nsh, CSR_VSATP);

• cfg->hedeleg = nacl_csr_read(nsh, CSR_HEDELEG);
  

  } else { csr->vsstatus = csr_read(CSR_VSSTATUS); csr->vsie = csr_read(CSR_VSIE);

@@ -681,6 +683,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) csr->vstval = csr_read(CSR_VSTVAL); csr->hvip = csr_read(CSR_HVIP); csr->vsatp = csr_read(CSR_VSATP);

• cfg->hedeleg = csr_read(CSR_HEDELEG);
  

  }

} diff --git a/arch/riscv/kvm/vcpu_sbi_fwft.c b/arch/riscv/kvm/vcpu_sbi_fwft.c index b0f66c7bf010..237edaefa267 100644 --- a/arch/riscv/kvm/vcpu_sbi_fwft.c +++ b/arch/riscv/kvm/vcpu_sbi_fwft.c @@ -14,6 +14,8 @@ #include <asm/kvm_vcpu_sbi.h> #include <asm/kvm_vcpu_sbi_fwft.h> +#define MIS_DELEG (BIT_ULL(EXC_LOAD_MISALIGNED) | BIT_ULL(EXC_STORE_MISALIGNED))

struct kvm_sbi_fwft_feature { /** * @id: Feature ID @@ -68,7 +70,41 @@ static bool kvm_fwft_is_defined_feature(enum sbi_fwft_feature_t feature) return false; } +static bool kvm_sbi_fwft_misaligned_delegation_supported(struct kvm_vcpu *vcpu) +{

• return misaligned_traps_can_delegate();

+}

+static long kvm_sbi_fwft_set_misaligned_delegation(struct kvm_vcpu *vcpu,

• 			struct kvm_sbi_fwft_config *conf,
  

• 			unsigned long value)
  

+{

• if (value == 1)

• csr_set(CSR_HEDELEG, MIS_DELEG);
  

• else if (value == 0)

• csr_clear(CSR_HEDELEG, MIS_DELEG);
  

• else

• return SBI_ERR_INVALID_PARAM;
  

• return SBI_SUCCESS;

+}

+static long kvm_sbi_fwft_get_misaligned_delegation(struct kvm_vcpu *vcpu,

• 			struct kvm_sbi_fwft_config *conf,
  

• 			unsigned long *value)
  

+{

• *value = (csr_read(CSR_HEDELEG) & MIS_DELEG) != 0;

This should be

(csr_read(CSR_HEDELEG) & MIS_DELEG) == MIS_DELEG;

Hum yeah indeed, I didn't thought that someone would ony delegate load or stores.

I'll fix that,

Thanks,

Clément

...

• return SBI_SUCCESS;

+}

static const struct kvm_sbi_fwft_feature features[] = {

• {

• .id = SBI_FWFT_MISALIGNED_EXC_DELEG,
  

• .supported = kvm_sbi_fwft_misaligned_delegation_supported,
  

• .set = kvm_sbi_fwft_set_misaligned_delegation,
  

• .get = kvm_sbi_fwft_get_misaligned_delegation,
  

• },

}; static struct kvm_sbi_fwft_config * -- 2.49.0

Thanks, drew