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Date: Wed, 6 Dec 2023 16:43:04 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: isaku.yamahata@...el.com
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
isaku.yamahata@...il.com, Paolo Bonzini <pbonzini@...hat.com>,
erdemaktas@...gle.com, Sean Christopherson <seanjc@...gle.com>,
Sagi Shahar <sagis@...gle.com>,
David Matlack <dmatlack@...gle.com>,
Kai Huang <kai.huang@...el.com>,
Zhi Wang <zhi.wang.linux@...il.com>, chen.bo@...el.com,
hang.yuan@...el.com, tina.zhang@...el.com,
Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [PATCH v17 018/116] KVM: TDX: x86: Add ioctl to get TDX
systemwide parameters
On 11/7/2023 10:55 PM, isaku.yamahata@...el.com wrote:
> From: Sean Christopherson <sean.j.christopherson@...el.com>
>
> Implement an ioctl to get system-wide parameters for TDX. Although the
> function is systemwide, vm scoped mem_enc ioctl works for userspace VMM
> like qemu and device scoped version is not define, re-use vm scoped
> mem_enc.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> ---
> v14 -> v15:
> - ABI change: added supported_gpaw and reserved area,
> ---
> arch/x86/include/uapi/asm/kvm.h | 24 ++++++++++
> arch/x86/kvm/vmx/tdx.c | 64 +++++++++++++++++++++++++++
> tools/arch/x86/include/uapi/asm/kvm.h | 52 ++++++++++++++++++++++
> 3 files changed, 140 insertions(+)
>
> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
> index 615fb60b3717..3fbd43d5177b 100644
> --- a/arch/x86/include/uapi/asm/kvm.h
> +++ b/arch/x86/include/uapi/asm/kvm.h
> @@ -593,4 +593,28 @@ struct kvm_tdx_cmd {
> __u64 error;
> };
>
> +struct kvm_tdx_cpuid_config {
> + __u32 leaf;
> + __u32 sub_leaf;
> + __u32 eax;
> + __u32 ebx;
> + __u32 ecx;
> + __u32 edx;
> +};
> +
> +struct kvm_tdx_capabilities {
> + __u64 attrs_fixed0;
> + __u64 attrs_fixed1;
> + __u64 xfam_fixed0;
> + __u64 xfam_fixed1;
> +#define TDX_CAP_GPAW_48 (1 << 0)
> +#define TDX_CAP_GPAW_52 (1 << 1)
> + __u32 supported_gpaw;
> + __u32 padding;
> + __u64 reserved[251];
> +
> + __u32 nr_cpuid_configs;
> + struct kvm_tdx_cpuid_config cpuid_configs[];
> +};
> +
> #endif /* _ASM_X86_KVM_H */
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index ead229e34813..f9e80582865d 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -6,6 +6,7 @@
> #include "capabilities.h"
> #include "x86_ops.h"
> #include "x86.h"
> +#include "mmu.h"
> #include "tdx.h"
>
> #undef pr_fmt
> @@ -16,6 +17,66 @@
> offsetof(struct tdsysinfo_struct, cpuid_configs)) \
> / sizeof(struct tdx_cpuid_config))
>
> +static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd)
> +{
> + struct kvm_tdx_capabilities __user *user_caps;
> + const struct tdsysinfo_struct *tdsysinfo;
> + struct kvm_tdx_capabilities *caps = NULL;
> + int ret = 0;
> +
> + BUILD_BUG_ON(sizeof(struct kvm_tdx_cpuid_config) !=
> + sizeof(struct tdx_cpuid_config));
> +
> + if (cmd->flags)
> + return -EINVAL;
> +
> + tdsysinfo = tdx_get_sysinfo();
> + if (!tdsysinfo)
> + return -EOPNOTSUPP;
> +
> + caps = kmalloc(sizeof(*caps), GFP_KERNEL);
> + if (!caps)
> + return -ENOMEM;
> +
> + user_caps = (void __user *)cmd->data;
> + if (copy_from_user(caps, user_caps, sizeof(*caps))) {
> + ret = -EFAULT;
> + goto out;
> + }
> +
> + if (caps->nr_cpuid_configs < tdsysinfo->num_cpuid_config) {
> + ret = -E2BIG;
> + goto out;
> + }
> +
> + *caps = (struct kvm_tdx_capabilities) {
> + .attrs_fixed0 = tdsysinfo->attributes_fixed0,
> + .attrs_fixed1 = tdsysinfo->attributes_fixed1,
> + .xfam_fixed0 = tdsysinfo->xfam_fixed0,
> + .xfam_fixed1 = tdsysinfo->xfam_fixed1,
> + .supported_gpaw = TDX_CAP_GPAW_48 |
> + (kvm_get_shadow_phys_bits() >= 52 &&
> + cpu_has_vmx_ept_5levels()) ? TDX_CAP_GPAW_52 : 0,
> + .nr_cpuid_configs = tdsysinfo->num_cpuid_config,
> + .padding = 0,
> + };
> +
> + if (copy_to_user(user_caps, caps, sizeof(*caps))) {
> + ret = -EFAULT;
> + goto out;
> + }
> + if (copy_to_user(user_caps->cpuid_configs, &tdsysinfo->cpuid_configs,
> + tdsysinfo->num_cpuid_config *
> + sizeof(struct tdx_cpuid_config))) {
> + ret = -EFAULT;
> + }
> +
> +out:
> + /* kfree() accepts NULL. */
> + kfree(caps);
> + return ret;
> +}
> +
> int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
> {
> struct kvm_tdx_cmd tdx_cmd;
> @@ -29,6 +90,9 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
> mutex_lock(&kvm->lock);
>
> switch (tdx_cmd.id) {
> + case KVM_TDX_CAPABILITIES:
> + r = tdx_get_capabilities(&tdx_cmd);
> + break;
> default:
> r = -EINVAL;
> goto out;
> diff --git a/tools/arch/x86/include/uapi/asm/kvm.h b/tools/arch/x86/include/uapi/asm/kvm.h
> index 1a6a1f987949..7a08723e99e2 100644
> --- a/tools/arch/x86/include/uapi/asm/kvm.h
> +++ b/tools/arch/x86/include/uapi/asm/kvm.h
According to the discussion, Sean's preference is "never update KVM's
uapi headers in tools/ in KVM's tree"
https://lore.kernel.org/all/Y8bZ%2FJ98V5i3wG%2Fv@google.com/
> @@ -562,4 +562,56 @@ struct kvm_pmu_event_filter {
> /* x86-specific KVM_EXIT_HYPERCALL flags. */
> #define KVM_EXIT_HYPERCALL_LONG_MODE BIT(0)
>
> +/* Trust Domain eXtension sub-ioctl() commands. */
> +enum kvm_tdx_cmd_id {
> + KVM_TDX_CAPABILITIES = 0,
> +
> + KVM_TDX_CMD_NR_MAX,
> +};
> +
> +struct kvm_tdx_cmd {
> + /* enum kvm_tdx_cmd_id */
> + __u32 id;
> + /* flags for sub-commend. If sub-command doesn't use this, set zero. */
> + __u32 flags;
> + /*
> + * data for each sub-command. An immediate or a pointer to the actual
> + * data in process virtual address. If sub-command doesn't use it,
> + * set zero.
> + */
> + __u64 data;
> + /*
> + * Auxiliary error code. The sub-command may return TDX SEAMCALL
> + * status code in addition to -Exxx.
> + * Defined for consistency with struct kvm_sev_cmd.
> + */
> + __u64 error;
> + /* Reserved: Defined for consistency with struct kvm_sev_cmd. */
> + __u64 unused;
> +};
> +
> +struct kvm_tdx_cpuid_config {
> + __u32 leaf;
> + __u32 sub_leaf;
> + __u32 eax;
> + __u32 ebx;
> + __u32 ecx;
> + __u32 edx;
> +};
> +
> +struct kvm_tdx_capabilities {
> + __u64 attrs_fixed0;
> + __u64 attrs_fixed1;
> + __u64 xfam_fixed0;
> + __u64 xfam_fixed1;
> +#define TDX_CAP_GPAW_48 (1 << 0)
> +#define TDX_CAP_GPAW_52 (1 << 1)
> + __u32 supported_gpaw;
> + __u32 padding;
> + __u64 reserved[251];
> +
> + __u32 nr_cpuid_configs;
> + struct kvm_tdx_cpuid_config cpuid_configs[];
> +};
> +
> #endif /* _ASM_X86_KVM_H */
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