[PATCH] x86/virt/tdx: Export TD config params of TDX module via sysfs

From: Isaku Yamahata
Date: Thu Mar 30 2023 - 03:05:03 EST

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TDX module has parameters for VMM to configure TD. User space VMM, e.g.
qemu, needs to know it. Export them to user space via sysfs.

TDX 1.0 provides TDH.SYS.INFO to provide system information in
TDSYSINFO_STRUCT. Its future extensibility is limited because of its
struct. From TDX 1.5, TDH.SYS.RD(metadata field_id) to read the info
specified by field id. So instead of exporting TDSYSINFO_STRUCT, adapt
metadata way to export those system information.

Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
Documentation/ABI/testing/sysfs-firmware-tdx | 23 +++
arch/x86/include/asm/tdx.h | 33 ++++
arch/x86/virt/vmx/tdx/tdx.c | 164 +++++++++++++++++++
arch/x86/virt/vmx/tdx/tdx.h | 18 ++
4 files changed, 238 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-firmware-tdx

diff --git a/Documentation/ABI/testing/sysfs-firmware-tdx b/Documentation/ABI/testing/sysfs-firmware-tdx
new file mode 100644
index 000000000000..1f26fb178144
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-tdx
@@ -0,0 +1,23 @@
+What: /sys/firmware/tdx/tdx_module/metadata
+Date: March 2023
+KernelVersion: 6.3
+Contact: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>, kvm@xxxxxxxxxxxxxxx
+Users: qemu, libvirt
+Description:
+ The TDX feature requires a firmware that is known as the TDX
+ module. The TDX module exposes its metadata in the following
+ read-only files. The information corresponds to the TDX global
+ metadata specified by 64bit field id. The file name is hex
+ string in lower case. The value is binary.
+ User space VMM like qemu needs refer to them to determine what
+ parameters are needed or allowed to configure guest TDs.
+
+ ================== ============================================
+ 1900000300000000 ATTRIBUTES_FIXED0
+ 1900000300000001 ATTRIBUTES_FIXED1
+ 1900000300000002 XFAM_FIXED0
+ 1900000300000003 XFAM_FIXED1
+ 9900000100000004 NUM_CPUID_CONFIG
+ 9900000300000400 CPUID_LEAVES
+ 9900000300000500 CPUID_VALUES
+ ================== ============================================
\ No newline at end of file
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 05870e5ed131..c650ac22a916 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -110,6 +110,39 @@ struct tdx_cpuid_config {
u32 edx;
} __packed;

+struct tdx_cpuid_config_leaf {
+ u32 leaf;
+ u32 sub_leaf;
+} __packed;
+static_assert(offsetof(struct tdx_cpuid_config, leaf) ==
+ offsetof(struct tdx_cpuid_config_leaf, leaf));
+static_assert(offsetof(struct tdx_cpuid_config, sub_leaf) ==
+ offsetof(struct tdx_cpuid_config_leaf, sub_leaf));
+static_assert(offsetofend(struct tdx_cpuid_config, sub_leaf) ==
+ sizeof(struct tdx_cpuid_config_leaf));
+
+struct tdx_cpuid_config_value {
+ u32 eax;
+ u32 ebx;
+ u32 ecx;
+ u32 edx;
+} __packed;
+static_assert(offsetof(struct tdx_cpuid_config, eax) -
+ offsetof(struct tdx_cpuid_config, eax) ==
+ offsetof(struct tdx_cpuid_config_value, eax));
+static_assert(offsetof(struct tdx_cpuid_config, ebx) -
+ offsetof(struct tdx_cpuid_config, eax) ==
+ offsetof(struct tdx_cpuid_config_value, ebx));
+static_assert(offsetof(struct tdx_cpuid_config, ecx) -
+ offsetof(struct tdx_cpuid_config, eax) ==
+ offsetof(struct tdx_cpuid_config_value, ecx));
+static_assert(offsetof(struct tdx_cpuid_config, edx) -
+ offsetof(struct tdx_cpuid_config, eax) ==
+ offsetof(struct tdx_cpuid_config_value, edx));
+static_assert(offsetofend(struct tdx_cpuid_config, edx) -
+ offsetof(struct tdx_cpuid_config, eax) ==
+ sizeof(struct tdx_cpuid_config_value));
+
#define TDSYSINFO_STRUCT_SIZE 1024
#define TDSYSINFO_STRUCT_ALIGNMENT 1024

diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index f9f9c1b76501..56ca520d67d6 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -33,6 +33,12 @@
#include <asm/tdx.h>
#include "tdx.h"

+#ifdef CONFIG_SYSFS
+static int tdx_sysfs_init(void);
+#else
+static inline int tdx_sysfs_init(void) { return 0;}
+#endif
+
u32 tdx_global_keyid __ro_after_init;
EXPORT_SYMBOL_GPL(tdx_global_keyid);
static u32 tdx_guest_keyid_start __ro_after_init;
@@ -399,6 +405,10 @@ static int __tdx_get_sysinfo(struct tdsysinfo_struct *sysinfo,
if (ret)
return ret;

+ ret = tdx_sysfs_init();
+ if (ret)
+ return ret;
+
pr_info("TDX module: atributes 0x%x, vendor_id 0x%x, major_version %u, minor_version %u, build_date %u, build_num %u",
sysinfo->attributes, sysinfo->vendor_id,
sysinfo->major_version, sysinfo->minor_version,
@@ -1367,3 +1377,157 @@ int tdx_enable(void)
return ret;
}
EXPORT_SYMBOL_GPL(tdx_enable);
+
+#ifdef CONFIG_SYSFS
+
+static struct kobject *tdx_kobj;
+static struct kobject *tdx_module_kobj;
+static struct kobject *tdx_metadata_kobj;
+
+#define TDX_METADATA_ATTR(_name, field_id_name, _size) \
+static struct bin_attribute tdx_metadata_ ## _name = { \
+ .attr = { \
+ .name = field_id_name, \
+ .mode = 0444, \
+ }, \
+ .size = _size, \
+ .read = tdx_metadata_ ## _name ## _show, \
+}
+
+#define TDX_METADATA_ATTR_SHOW(_name, field_id_name) \
+static ssize_t tdx_metadata_ ## _name ## _show(struct file *filp, struct kobject *kobj, \
+ struct bin_attribute *bin_attr, \
+ char *buf, loff_t offset, size_t count) \
+{ \
+ struct tdsysinfo_struct *sysinfo = &PADDED_STRUCT(tdsysinfo); \
+ \
+ return memory_read_from_buffer(buf, count, &offset, \
+ &sysinfo->_name, \
+ sizeof(sysinfo->_name)); \
+} \
+TDX_METADATA_ATTR(_name, field_id_name, sizeof_field(struct tdsysinfo_struct, _name))
+
+TDX_METADATA_ATTR_SHOW(attributes_fixed0, TDX_METADATA_ATTRIBUTES_FIXED0_NAME);
+TDX_METADATA_ATTR_SHOW(attributes_fixed1, TDX_METADATA_ATTRIBUTES_FIXED1_NAME);
+TDX_METADATA_ATTR_SHOW(xfam_fixed0, TDX_METADATA_XFAM_FIXED0_NAME);
+TDX_METADATA_ATTR_SHOW(xfam_fixed1, TDX_METADATA_XFAM_FIXED1_NAME);
+
+static ssize_t tdx_metadata_num_cpuid_config_show(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *bin_attr,
+ char *buf, loff_t offset, size_t count)
+{
+ struct tdsysinfo_struct *sysinfo = &PADDED_STRUCT(tdsysinfo);
+ /*
+ * Although tdsysinfo_struct.num_cpuid_config is defined as u32 for
+ * alignment, TDX 1.5 defines metadata NUM_CONFIG_CPUID as u16.
+ */
+ u16 tmp = (u16)sysinfo->num_cpuid_config;
+
+ WARN_ON_ONCE(tmp != sysinfo->num_cpuid_config);
+ return memory_read_from_buffer(buf, count, &offset, &tmp, sizeof(tmp));
+}
+TDX_METADATA_ATTR(num_cpuid_config, TDX_METADATA_NUM_CPUID_CONFIG_NAME, sizeof(u16));
+
+static ssize_t tdx_metadata_cpuid_leaves_show(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *bin_attr, char *buf,
+ loff_t offset, size_t count)
+{
+ struct tdsysinfo_struct *sysinfo = &PADDED_STRUCT(tdsysinfo);
+ ssize_t r;
+ struct tdx_cpuid_config_leaf *tmp;
+ u32 i;
+
+ tmp = kmalloc(bin_attr->size, GFP_KERNEL);
+ if (!tmp)
+ return -ENOMEM;
+
+ for (i = 0; i < sysinfo->num_cpuid_config; i++) {
+ struct tdx_cpuid_config *c = &sysinfo->cpuid_configs[i];
+ struct tdx_cpuid_config_leaf *leaf = (struct tdx_cpuid_config_leaf *)c;
+
+ memcpy(tmp + i, leaf, sizeof(*leaf));
+ }
+
+ r = memory_read_from_buffer(buf, count, &offset, tmp, bin_attr->size);
+ kfree(tmp);
+ return r;
+}
+
+TDX_METADATA_ATTR(cpuid_leaves, TDX_METADATA_CPUID_LEAVES_NAME, 0);
+
+static ssize_t tdx_metadata_cpuid_values_show(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *bin_attr, char *buf,
+ loff_t offset, size_t count)
+{
+ struct tdsysinfo_struct *sysinfo = &PADDED_STRUCT(tdsysinfo);
+ struct tdx_cpuid_config_value *tmp;
+ ssize_t r;
+ u32 i;
+
+ tmp = kmalloc(bin_attr->size, GFP_KERNEL);
+ if (!tmp)
+ return -ENOMEM;
+
+ for (i = 0; i < sysinfo->num_cpuid_config; i++) {
+ struct tdx_cpuid_config *c = &sysinfo->cpuid_configs[i];
+ struct tdx_cpuid_config_value *value = (struct tdx_cpuid_config_value *)&c->eax;
+
+ memcpy(tmp + i, value, sizeof(*value));
+ }
+
+ r = memory_read_from_buffer(buf, count, &offset, tmp, bin_attr->size);
+ kfree(tmp);
+ return r;
+}
+
+TDX_METADATA_ATTR(cpuid_values, TDX_METADATA_CPUID_VALUES_NAME, 0);
+
+static struct bin_attribute *tdx_metadata_attrs[] = {
+ &tdx_metadata_attributes_fixed0,
+ &tdx_metadata_attributes_fixed1,
+ &tdx_metadata_xfam_fixed0,
+ &tdx_metadata_xfam_fixed1,
+ &tdx_metadata_num_cpuid_config,
+ &tdx_metadata_cpuid_leaves,
+ &tdx_metadata_cpuid_values,
+ NULL,
+};
+
+static const struct attribute_group tdx_metadata_attr_group = {
+ .bin_attrs = tdx_metadata_attrs,
+};
+
+static int tdx_sysfs_init(void)
+{
+ struct tdsysinfo_struct *sysinfo;
+ int ret;
+
+ tdx_kobj = kobject_create_and_add("tdx", firmware_kobj);
+ if (!tdx_kobj) {
+ pr_err("kobject_create_and_add tdx failed\n");
+ return -EINVAL;
+ }
+
+ tdx_module_kobj = kobject_create_and_add("tdx_module", tdx_kobj);
+ if (!tdx_module_kobj) {
+ pr_err("kobject_create_and_add tdx_module failed\n");
+ return -EINVAL;
+ }
+ tdx_metadata_kobj = kobject_create_and_add("metadata", tdx_module_kobj);
+ if (!tdx_metadata_kobj) {
+ pr_err("Sysfs exporting tdx global metadata failed %d\n", ret);
+ return -EINVAL;
+ }
+
+ sysinfo = &PADDED_STRUCT(tdsysinfo);
+ tdx_metadata_cpuid_leaves.size = sysinfo->num_cpuid_config *
+ sizeof(struct tdx_cpuid_config_leaf);
+ tdx_metadata_cpuid_values.size = sysinfo->num_cpuid_config *
+ sizeof(struct tdx_cpuid_config_value);
+ ret = sysfs_create_group(tdx_metadata_kobj, &tdx_metadata_attr_group);
+ if (ret)
+ pr_err("Sysfs exporting tdx module attributes failed %d\n", ret);
+
+ return ret;
+}
+#endif
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index db0cbcceb5b3..a48f38fe6cc4 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -93,4 +93,22 @@ struct tdmr_info_list {
int max_tdmrs; /* How many 'tdmr_info's are allocated */
};

+/* TDX metadata base field id. */
+#define TDX_METADATA_ATTRIBUTES_FIXED0 0x1900000300000000ULL
+#define TDX_METADATA_ATTRIBUTES_FIXED1 0x1900000300000001ULL
+#define TDX_METADATA_XFAM_FIXED0 0x1900000300000002ULL
+#define TDX_METADATA_XFAM_FIXED1 0x1900000300000003ULL
+#define TDX_METADATA_NUM_CPUID_CONFIG 0x9900000100000004ULL
+#define TDX_METADATA_CPUID_LEAVES 0x9900000300000400ULL
+#define TDX_METADATA_CPUID_VALUES 0x9900000300000500ULL
+
+/* File name for sysfs: hex with lower case. */
+#define TDX_METADATA_ATTRIBUTES_FIXED0_NAME "1900000300000000"
+#define TDX_METADATA_ATTRIBUTES_FIXED1_NAME "1900000300000001"
+#define TDX_METADATA_XFAM_FIXED0_NAME "1900000300000002"
+#define TDX_METADATA_XFAM_FIXED1_NAME "1900000300000003"
+#define TDX_METADATA_NUM_CPUID_CONFIG_NAME "9900000100000004"
+#define TDX_METADATA_CPUID_LEAVES_NAME "9900000300000400"
+#define TDX_METADATA_CPUID_VALUES_NAME "9900000300000500"
+
#endif
--
2.25.1

--
Isaku Yamahata <isaku.yamahata@xxxxxxxxx>

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