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Message-Id: <20220422150519.3818093-1-atishp@rivosinc.com>
Date: Fri, 22 Apr 2022 08:05:19 -0700
From: Atish Patra <atishp@...osinc.com>
To: kvm@...r.kernel.org
Cc: Atish Patra <atishp@...osinc.com>,
Atish Patra <atishp@...shpatra.org>,
Anup Patel <anup@...infault.org>, devicetree@...r.kernel.org,
Jisheng Zhang <jszhang@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
Palmer Dabbelt <palmer@...belt.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Rob Herring <robh+dt@...nel.org>, kvm-riscv@...ts.infradead.org
Subject: [v2 PATCH] RISC-V: KVM: Introduce ISA extension register
Currently, there is no provision for vmm (qemu-kvm or kvmtool) to
query about multiple-letter ISA extensions. The config register
is only used for base single letter ISA extensions.
A new ISA extension register is added that will allow the vmm
to query about any ISA extension one at a time. It is enabled for
both single letter or multi-letter ISA extensions. The ISA extension
register is useful to if the vmm requires to retrieve/set single
extension while the config register should be used if all the base
ISA extension required to retrieve or set.
For any multi-letter ISA extensions, the new register interface
must be used.
Signed-off-by: Atish Patra <atishp@...osinc.com>
---
Changes from v1->v2:
1. Sending the patch separate from sstc series as it is unrelated.
2. Removed few redundant lines.
The kvm tool patches can be found here.
https://github.com/atishp04/kvmtool/tree/sstc_v2
---
arch/riscv/include/uapi/asm/kvm.h | 20 +++++++
arch/riscv/kvm/vcpu.c | 98 +++++++++++++++++++++++++++++++
2 files changed, 118 insertions(+)
diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index f808ad1ce500..92bd469e2ba6 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -82,6 +82,23 @@ struct kvm_riscv_timer {
__u64 state;
};
+/**
+ * ISA extension IDs specific to KVM. This is not the same as the host ISA
+ * extension IDs as that is internal to the host and should not be exposed
+ * to the guest. This should always be contiguous to keep the mapping simple
+ * in KVM implementation.
+ */
+enum KVM_RISCV_ISA_EXT_ID {
+ KVM_RISCV_ISA_EXT_A = 0,
+ KVM_RISCV_ISA_EXT_C,
+ KVM_RISCV_ISA_EXT_D,
+ KVM_RISCV_ISA_EXT_F,
+ KVM_RISCV_ISA_EXT_H,
+ KVM_RISCV_ISA_EXT_I,
+ KVM_RISCV_ISA_EXT_M,
+ KVM_RISCV_ISA_EXT_MAX,
+};
+
/* Possible states for kvm_riscv_timer */
#define KVM_RISCV_TIMER_STATE_OFF 0
#define KVM_RISCV_TIMER_STATE_ON 1
@@ -123,6 +140,9 @@ struct kvm_riscv_timer {
#define KVM_REG_RISCV_FP_D_REG(name) \
(offsetof(struct __riscv_d_ext_state, name) / sizeof(__u64))
+/* ISA Extension registers are mapped as type 7 */
+#define KVM_REG_RISCV_ISA_EXT (0x07 << KVM_REG_RISCV_TYPE_SHIFT)
+
#endif
#endif /* __LINUX_KVM_RISCV_H */
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index aad430668bb4..93492eb292fd 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -365,6 +365,100 @@ static int kvm_riscv_vcpu_set_reg_csr(struct kvm_vcpu *vcpu,
return 0;
}
+/* Mapping between KVM ISA Extension ID & Host ISA extension ID */
+static unsigned long kvm_isa_ext_arr[] = {
+ RISCV_ISA_EXT_a,
+ RISCV_ISA_EXT_c,
+ RISCV_ISA_EXT_d,
+ RISCV_ISA_EXT_f,
+ RISCV_ISA_EXT_h,
+ RISCV_ISA_EXT_i,
+ RISCV_ISA_EXT_m,
+};
+
+static int kvm_riscv_vcpu_get_reg_isa_ext(struct kvm_vcpu *vcpu,
+ const struct kvm_one_reg *reg)
+{
+ unsigned long __user *uaddr =
+ (unsigned long __user *)(unsigned long)reg->addr;
+ unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
+ KVM_REG_SIZE_MASK |
+ KVM_REG_RISCV_ISA_EXT);
+ unsigned long reg_val = 0;
+ unsigned long host_isa_ext;
+
+ if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
+ return -EINVAL;
+
+ if (reg_num >= KVM_RISCV_ISA_EXT_MAX || reg_num >= ARRAY_SIZE(kvm_isa_ext_arr))
+ return -EINVAL;
+
+ host_isa_ext = kvm_isa_ext_arr[reg_num];
+ if (__riscv_isa_extension_available(NULL, host_isa_ext))
+ reg_val = 1; /* Mark the given extension as available */
+
+ if (copy_to_user(uaddr, ®_val, KVM_REG_SIZE(reg->id)))
+ return -EFAULT;
+
+ return 0;
+}
+
+static int kvm_riscv_vcpu_set_reg_isa_ext(struct kvm_vcpu *vcpu,
+ const struct kvm_one_reg *reg)
+{
+ unsigned long __user *uaddr =
+ (unsigned long __user *)(unsigned long)reg->addr;
+ unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
+ KVM_REG_SIZE_MASK |
+ KVM_REG_RISCV_ISA_EXT);
+ unsigned long reg_val;
+ unsigned long host_isa_ext;
+ unsigned long host_isa_ext_mask;
+
+ if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
+ return -EINVAL;
+
+ if (reg_num >= KVM_RISCV_ISA_EXT_MAX || reg_num >= ARRAY_SIZE(kvm_isa_ext_arr))
+ return -EINVAL;
+
+ if (copy_from_user(®_val, uaddr, KVM_REG_SIZE(reg->id)))
+ return -EFAULT;
+
+ host_isa_ext = kvm_isa_ext_arr[reg_num];
+ if (!__riscv_isa_extension_available(NULL, host_isa_ext))
+ return -EOPNOTSUPP;
+
+ if (host_isa_ext >= RISCV_ISA_EXT_BASE &&
+ host_isa_ext < RISCV_ISA_EXT_MAX) {
+ /** Multi-letter ISA extension. Currently there is no provision
+ * to enable/disable the multi-letter ISA extensions for guests.
+ * Return success if the request is to enable any ISA extension
+ * that is available in the hardware.
+ * Return -EOPNOTSUPP otherwise.
+ */
+ if (!reg_val)
+ return -EOPNOTSUPP;
+ else
+ return 0;
+ }
+
+ /* Single letter base ISA extension */
+ if (!vcpu->arch.ran_atleast_once) {
+ host_isa_ext_mask = BIT_MASK(host_isa_ext);
+ if (!reg_val && (host_isa_ext_mask & KVM_RISCV_ISA_DISABLE_ALLOWED))
+ vcpu->arch.isa &= ~host_isa_ext_mask;
+ else
+ vcpu->arch.isa |= host_isa_ext_mask;
+ vcpu->arch.isa &= riscv_isa_extension_base(NULL);
+ vcpu->arch.isa &= KVM_RISCV_ISA_ALLOWED;
+ kvm_riscv_vcpu_fp_reset(vcpu);
+ } else {
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+
static int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg)
{
@@ -382,6 +476,8 @@ static int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu,
else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_FP_D)
return kvm_riscv_vcpu_set_reg_fp(vcpu, reg,
KVM_REG_RISCV_FP_D);
+ else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_ISA_EXT)
+ return kvm_riscv_vcpu_set_reg_isa_ext(vcpu, reg);
return -EINVAL;
}
@@ -403,6 +499,8 @@ static int kvm_riscv_vcpu_get_reg(struct kvm_vcpu *vcpu,
else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_FP_D)
return kvm_riscv_vcpu_get_reg_fp(vcpu, reg,
KVM_REG_RISCV_FP_D);
+ else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_ISA_EXT)
+ return kvm_riscv_vcpu_get_reg_isa_ext(vcpu, reg);
return -EINVAL;
}
--
2.25.1
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