On 3/1/2024 7:20 PM, Kai Huang wrote:
KVM will need to read a bunch of non-TDMR related metadata to create and
run TDX guests. Export the metadata read infrastructure for KVM to use.
Specifically, export two helpers:
1) The helper which reads multiple metadata fields to a buffer of a
structure based on the "field ID -> structure member" mapping table.
2) The low level helper which just reads a given field ID.
How about introducing a helper to read a single metadata field comparing
to 1) instead of the low level helper.
The low level helper tdx_sys_metadata_field_read() requires the data buf
to be u64 *. So the caller needs to use a temporary variable and handle
the memcpy when the field is less than 8 bytes.
so why not expose a high level helper to read single field, e.g.,
+int tdx_sys_metadata_read_single(u64 field_id, int bytes, void *buf)
+{
+ return stbuf_read_sys_metadata_field(field_id, 0, bytes, buf);
+}
+EXPORT_SYMBOL_GPL(tdx_sys_metadata_read_single);
The two helpers cover cases when the user wants to cache a bunch of
metadata fields to a certain structure and when the user just wants to
query a specific metadata field on demand. They are enough for KVM to
use (and also should be enough for other potential users).
Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/tdx.h | 22 ++++++++++++++++++++++
arch/x86/virt/vmx/tdx/tdx.c | 25 ++++++++-----------------
2 files changed, 30 insertions(+), 17 deletions(-)
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index eba178996d84..709b9483f9e4 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -116,6 +116,28 @@ static inline u64 sc_retry(sc_func_t func, u64 fn,
int tdx_cpu_enable(void);
int tdx_enable(void);
const char *tdx_dump_mce_info(struct mce *m);
+
+struct tdx_metadata_field_mapping {
+ u64 field_id;
+ int offset;
+ int size;
+};
+
+#define TD_SYSINFO_MAP(_field_id, _struct, _member) \
+ { .field_id = MD_FIELD_ID_##_field_id, \
+ .offset = offsetof(_struct, _member), \
+ .size = sizeof(typeof(((_struct *)0)->_member)) }
+
+/*
+ * Read multiple global metadata fields to a buffer of a structure
+ * based on the "field ID -> structure member" mapping table.
+ */
+int tdx_sys_metadata_read(const struct tdx_metadata_field_mapping *fields,
+ int nr_fields, void *stbuf);
+
+/* Read a single global metadata field */
+int tdx_sys_metadata_field_read(u64 field_id, u64 *data);
+
#else
static inline void tdx_init(void) { }
static inline int tdx_cpu_enable(void) { return -ENODEV; }
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 4ee4b8cf377c..dc21310776ab 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -251,7 +251,7 @@ static int build_tdx_memlist(struct list_head *tmb_list)
return ret;
}
-static int read_sys_metadata_field(u64 field_id, u64 *data)
+int tdx_sys_metadata_field_read(u64 field_id, u64 *data)
{
struct tdx_module_args args = {};
int ret;
@@ -270,6 +270,7 @@ static int read_sys_metadata_field(u64 field_id, u64 *data)
return 0;
}
+EXPORT_SYMBOL_GPL(tdx_sys_metadata_field_read);
/* Return the metadata field element size in bytes */
static int get_metadata_field_bytes(u64 field_id)
@@ -295,7 +296,7 @@ static int stbuf_read_sys_metadata_field(u64 field_id,
if (WARN_ON_ONCE(get_metadata_field_bytes(field_id) != bytes))
return -EINVAL;
- ret = read_sys_metadata_field(field_id, &tmp);
+ ret = tdx_sys_metadata_field_read(field_id, &tmp);
if (ret)
return ret;
@@ -304,19 +305,8 @@ static int stbuf_read_sys_metadata_field(u64 field_id,
return 0;
}
-struct field_mapping {
- u64 field_id;
- int offset;
- int size;
-};
-
-#define TD_SYSINFO_MAP(_field_id, _struct, _member) \
- { .field_id = MD_FIELD_ID_##_field_id, \
- .offset = offsetof(_struct, _member), \
- .size = sizeof(typeof(((_struct *)0)->_member)) }
-
-static int read_sys_metadata(const struct field_mapping *fields, int nr_fields,
- void *stbuf)
+int tdx_sys_metadata_read(const struct tdx_metadata_field_mapping *fields,
+ int nr_fields, void *stbuf)
{
int i, ret;
@@ -331,6 +321,7 @@ static int read_sys_metadata(const struct field_mapping *fields, int nr_fields,
return 0;
}
+EXPORT_SYMBOL_GPL(tdx_sys_metadata_read);
#define TD_SYSINFO_MAP_TDMR_INFO(_field_id, _member) \
TD_SYSINFO_MAP(_field_id, struct tdx_tdmr_sysinfo, _member)
@@ -338,7 +329,7 @@ static int read_sys_metadata(const struct field_mapping *fields, int nr_fields,
static int get_tdx_tdmr_sysinfo(struct tdx_tdmr_sysinfo *tdmr_sysinfo)
{
/* Map TD_SYSINFO fields into 'struct tdx_tdmr_sysinfo': */
- const struct field_mapping fields[] = {
+ const struct tdx_metadata_field_mapping fields[] = {
TD_SYSINFO_MAP_TDMR_INFO(MAX_TDMRS, max_tdmrs),
TD_SYSINFO_MAP_TDMR_INFO(MAX_RESERVED_PER_TDMR, max_reserved_per_tdmr),
TD_SYSINFO_MAP_TDMR_INFO(PAMT_4K_ENTRY_SIZE, pamt_entry_size[TDX_PS_4K]),
@@ -347,7 +338,7 @@ static int get_tdx_tdmr_sysinfo(struct tdx_tdmr_sysinfo *tdmr_sysinfo)
};
/* Populate 'tdmr_sysinfo' fields using the mapping structure above: */
- return read_sys_metadata(fields, ARRAY_SIZE(fields), tdmr_sysinfo);
+ return tdx_sys_metadata_read(fields, ARRAY_SIZE(fields), tdmr_sysinfo);
}
/* Calculate the actual TDMR size */
