[PATCH 6.8 519/715] RISC-V: KVM: Forward SEED CSR access to user space

Sasha Levin
2024-03-24T22:43:32Z

From: Anup Patel <apatel@ventanamicro.com>

[ Upstream commit d808f0b1be4888a87524164bc7dad2242734de38 ]

The SEED CSR access from VS/VU mode (guest) will always trap to
HS-mode (KVM) when Zkr extension is available to the Guest/VM.

Forward this CSR access to KVM user space so that it can be
emulated based on the method chosen by VMM.

Fixes: f370b4e668f0 ("RISC-V: KVM: Allow scalar crypto extensions for Guest/VM")
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/riscv/kvm/vcpu_insn.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/arch/riscv/kvm/vcpu_insn.c b/arch/riscv/kvm/vcpu_insn.c
index 7a6abed41bc17..ee7215f4071f5 100644
--- a/arch/riscv/kvm/vcpu_insn.c
+++ b/arch/riscv/kvm/vcpu_insn.c
@@ -7,6 +7,8 @@
#include <linux/bitops.h>
#include <linux/kvm_host.h>

+#include <asm/cpufeature.h>
+
#define INSN_OPCODE_MASK 0x007c
#define INSN_OPCODE_SHIFT 2
#define INSN_OPCODE_SYSTEM 28
@@ -213,9 +215,20 @@ struct csr_func {
unsigned long wr_mask);
};

+static int seed_csr_rmw(struct kvm_vcpu *vcpu, unsigned int csr_num,
+ unsigned long *val, unsigned long new_val,
+ unsigned long wr_mask)
+{
+ if (!riscv_isa_extension_available(vcpu->arch.isa, ZKR))
+ return KVM_INSN_ILLEGAL_TRAP;
+
+ return KVM_INSN_EXIT_TO_USER_SPACE;
+}
+
static const struct csr_func csr_funcs[] = {
KVM_RISCV_VCPU_AIA_CSR_FUNCS
KVM_RISCV_VCPU_HPMCOUNTER_CSR_FUNCS
+ { .base = CSR_SEED, .count = 1, .func = seed_csr_rmw },
};

/**
--
2.43.0