On 4/24/25 10:32 AM, 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 <[email protected]>
Reviewed-by: Deepak Gupta <[email protected]>
Reviewed-by: Andrew Jones <[email protected]>
---
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);
Can we avoid saving hedeleg in vcpu_put path by updating the
cfg->hedeleg in kvm_sbi_fwft_set_misaligned_delegation.
We already update the hedeleg in vcpu_load path from cfg->hedeleg.
If the next vcpu did not enable delegation it will get the correct
config written to hedeleg.
This will save us a csr read cost in each VM exit path for something
that is probably configured once in guest life time.
}
}
diff --git a/arch/riscv/kvm/vcpu_sbi_fwft.c b/arch/riscv/kvm/vcpu_sbi_fwft.c
index b0f66c7bf010..d16ee477042f 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) == MIS_DELEG;
+
+ 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 *
