On Thu, 26 Aug 2021 09:54:29 +0100,
Andrew Jones <drjones@xxxxxxxxxx> wrote:
[...]
> I see Marc just replied stating we'll probably just have a single
> register. The KVM_GET_SUPPORTED_CPUID type of ioctl would be
> overkill in that case (get-one_reg is enough). Anyway it can
> always be added later if we expand into more registers.
Here's what I propose for the KVM-specific hypercalls. Compile tested
only, plenty of nits to sort out. But you'll get the general idea.
Something similar could be implemented for ARM-architected hypercalls
such as TRNG.
M.
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index f8be56d5342b..3fcca7cc9668 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -136,6 +136,9 @@ struct kvm_arch {
/* Memory Tagging Extension enabled for the guest */
bool mte_enabled;
+
+ /* Bitmap of enabled hypercalls */
+ unsigned long hc_bmap;
};
struct kvm_vcpu_fault_info {
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index b3edde68bc3e..8d7a1a93f12c 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -281,6 +281,9 @@ struct kvm_arm_copy_mte_tags {
#define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED 3
#define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED (1U << 4)
+#define KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_0 KVM_REG_ARM_FW_REG(3)
+#define KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_1 KVM_REG_ARM_FW_REG(4)
+
/* SVE registers */
#define KVM_REG_ARM64_SVE (0x15 << KVM_REG_ARM_COPROC_SHIFT)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index fe102cd2e518..dbc136675b02 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -130,6 +130,13 @@ static void set_default_spectre(struct kvm *kvm)
kvm->arch.pfr0_csv3 = 1;
}
+
+static void set_default_vendor_hypercalls(struct kvm *kvm)
+{
+ kvm->arch.hc_bmap = (BIT(ARM_SMCCC_KVM_FUNC_FEATURES) |
+ BIT(ARM_SMCCC_KVM_FUNC_PTP));
+}
+
/**
* kvm_arch_init_vm - initializes a VM data structure
* @kvm: pointer to the KVM struct
@@ -156,6 +163,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
kvm->arch.max_vcpus = kvm_arm_default_max_vcpus();
set_default_spectre(kvm);
+ set_default_vendor_hypercalls(kvm);
return ret;
out_free_stage2_pgd:
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 30da78f72b3b..11f79e790f7d 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -127,8 +127,7 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
val[3] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3;
break;
case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
- val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES);
- val[0] |= BIT(ARM_SMCCC_KVM_FUNC_PTP);
+ val[0] = vcpu->kvm->arch.hc_bmap;
break;
case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
kvm_ptp_get_time(vcpu, val);
diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
index 74c47d420253..ceef0c706d50 100644
--- a/arch/arm64/kvm/psci.c
+++ b/arch/arm64/kvm/psci.c
@@ -404,21 +404,26 @@ int kvm_psci_call(struct kvm_vcpu *vcpu)
};
}
+static const u64 fw_reg_ids[] = {
+ KVM_REG_ARM_PSCI_VERSION,
+ KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1,
+ KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
+ KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_0,
+};
+
int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
{
- return 3; /* PSCI version and two workaround registers */
+ return ARRAY_SIZE(fw_reg_ids);
}
int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
{
- if (put_user(KVM_REG_ARM_PSCI_VERSION, uindices++))
- return -EFAULT;
-
- if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1, uindices++))
- return -EFAULT;
+ int i;
- if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2, uindices++))
- return -EFAULT;
+ for (i = 0; i < ARRAY_SIZE(fw_reg_ids); i++) {
+ if (put_user(fw_reg_ids[i], uindices++))
+ return -EFAULT;
+ }
return 0;
}
@@ -477,6 +482,10 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
break;
+ case KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_0:
+ val = vcpu->kvm->arch.hc_bmap;
+ break;
+ case KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_1:
default:
return -ENOENT;
}
@@ -515,8 +524,9 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
return -EINVAL;
vcpu->kvm->arch.psci_version = val;
return 0;
+ default:
+ return -EINVAL;
}
- break;
}
case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
@@ -563,9 +573,16 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
return -EINVAL;
return 0;
+ case KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_0:
+ /* FIXME: no vcpu should have run */
+ /* Exclude any unknown bit */
+ if (val & ~(BIT(ARM_SMCCC_KVM_FUNC_FEATURES) |
+ BIT(ARM_SMCCC_KVM_FUNC_PTP)))
+ return -EINVAL;
+ vcpu->kvm->arch.hc_bmap = val;
+ return 0;
+ case KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_1:
default:
return -ENOENT;
}
-
- return -EINVAL;
}
--
Without deviation from the norm, progress is not possible.
