Hi Shameer,
On 8/1/25 9:47 AM, Shameer Kolothum wrote:
> From: Shameer Kolothum <shameerali.kolothum.th...@huawei.com>
>
> The helper function will try to set the SMCCC filters for KVM vendor
> hypercalls related to target implementation CPU support. It also
> checks the kernel support for writable implementation ID registers
> (MIDR/REVIDR/AIDR) and enables it.
>
> Subsequent patches for Target Impl CPU support will make use of this
> helper.
>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.th...@huawei.com>
> ---
> target/arm/kvm.c | 72 ++++++++++++++++++++++++++++++++++++++++++++
> target/arm/kvm_arm.h | 12 ++++++++
> 2 files changed, 84 insertions(+)
>
> diff --git a/target/arm/kvm.c b/target/arm/kvm.c
> index 3f41f99e23..eb04640b50 100644
> --- a/target/arm/kvm.c
> +++ b/target/arm/kvm.c
> @@ -2072,6 +2072,78 @@ bool kvm_arm_mte_supported(void)
> return kvm_check_extension(kvm_state, KVM_CAP_ARM_MTE);
> }
>
> +static bool kvm_arm_set_vm_attr(struct kvm_device_attr *attr, const char
> *name)
> +{
> + int err;
> +
> + err = kvm_vm_ioctl(kvm_state, KVM_HAS_DEVICE_ATTR, attr);
> + if (err != 0) {
> + error_report("%s: KVM_HAS_DEVICE_ATTR: %s", name, strerror(-err));
> + return false;
> + }
> +
> + err = kvm_vm_ioctl(kvm_state, KVM_SET_DEVICE_ATTR, attr);
> + if (err != 0) {
> + error_report("%s: KVM_SET_DEVICE_ATTR: %s", name, strerror(-err));
> + return false;
> + }
> +
> + return true;
> +}
> +
> +static bool kvm_arm_set_smccc_filter(uint64_t func, uint8_t faction)
nit: base is _u32 in the kernel
> +{
> + struct kvm_smccc_filter filter = {
> + .base = func,
> + .nr_functions = 1,
> + .action = faction,
> + };
> + struct kvm_device_attr attr = {
> + .group = KVM_ARM_VM_SMCCC_CTRL,
> + .attr = KVM_ARM_VM_SMCCC_FILTER,
> + .flags = 0,
> + .addr = (uintptr_t)&filter,
> + };
> +
> + if (!kvm_arm_set_vm_attr(&attr, "SMCCC Filter")) {
> + error_report("failed to set SMCCC filter in KVM Host");
maybe also output @func in the error msg
> + return false;
> + }
> +
> + return true;
> +}
> +
> +bool kvm_arm_target_impl_cpus_supported(void)
> +{
> + if (!kvm_arm_set_smccc_filter(
> + ARM_SMCCC_VENDOR_HYP_KVM_DISCOVER_IMPL_VER_FUNC_ID,
> + KVM_SMCCC_FILTER_FWD_TO_USER)) {
> + error_report("ARM_SMCCC_KVM_FUNC_DISCOVER_IMPL_VER fwd filter "
> + "install failed");
> + return false;
> + }
> +
> + if (!kvm_arm_set_smccc_filter(
> + ARM_SMCCC_VENDOR_HYP_KVM_DISCOVER_IMPL_CPUS_FUNC_ID,
> + KVM_SMCCC_FILTER_FWD_TO_USER)) {
> + error_report("ARM_SMCCC_KVM_FUNC_DISCOVER_IMPL_CPUS fwd filter "
> + "install failed");
> + return false;
> + }
> +
> + if (!kvm_check_extension(kvm_state, KVM_CAP_ARM_WRITABLE_IMP_ID_REGS)) {
> + error_report("KVM_CAP_ARM_WRITABLE_IMP_ID_REGS not supported");
> + return false;
> + }
> +
> + if (kvm_vm_enable_cap(kvm_state, KVM_CAP_ARM_WRITABLE_IMP_ID_REGS, 0)) {
> + error_report("Failed to enable KVM_CAP_ARM_WRITABLE_IMP_ID_REGS
> cap");
> + return false;
> + }
> +
> + return true;
> +}
> +
> QEMU_BUILD_BUG_ON(KVM_ARM64_SVE_VQ_MIN != 1);
>
> uint32_t kvm_arm_sve_get_vls(ARMCPU *cpu)
> diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
> index ba5de45f86..3cd6447901 100644
> --- a/target/arm/kvm_arm.h
> +++ b/target/arm/kvm_arm.h
> @@ -207,6 +207,13 @@ bool kvm_arm_sve_supported(void);
> */
> bool kvm_arm_mte_supported(void);
>
> +/**
> + * kvm_arm_target_impl_cpus_supported:
> + *
> + * Returns: true if KVM can enable target impl CPUs, and false otherwise.
> + */
> +bool kvm_arm_target_impl_cpus_supported(void);
> +
> /**
> * kvm_arm_get_max_vm_ipa_size:
> * @ms: Machine state handle
> @@ -263,6 +270,11 @@ static inline bool kvm_arm_mte_supported(void)
> return false;
> }
>
> +static inline bool kvm_arm_target_impl_cpus_supported(void)
> +{
> + return false;
> +}
> +
> static inline int kvm_arm_get_writable_id_regs(ARMCPU *cpu, IdRegMap
> *idregmap)
> {
> return -ENOSYS;
Otherwise looks good to me.
Thanks
Eric
