[PATCH v19 004/130] x86/virt/tdx: Support global metadata read for all element sizes

isaku.yamahata
2024-02-26T08:27:37Z

From: Kai Huang <kai.huang@intel.com>

For now the kernel only reads TDMR related global metadata fields for
module initialization. All these fields are 16-bits, and the kernel
only supports reading 16-bits fields.

KVM will need to read a bunch of non-TDMR related metadata to create and
run TDX guests. It's essential to provide a generic metadata read
infrastructure which supports reading all 8/16/32/64 bits element sizes.

Extend the metadata read to support reading all these element sizes.

Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
arch/x86/virt/vmx/tdx/tdx.c | 59 +++++++++++++++++++++++++------------
arch/x86/virt/vmx/tdx/tdx.h | 2 --
2 files changed, 40 insertions(+), 21 deletions(-)

diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index eb208da4ff63..a19adc898df6 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -271,23 +271,35 @@ static int read_sys_metadata_field(u64 field_id, u64 *data)
return 0;
}

-static int read_sys_metadata_field16(u64 field_id,
- int offset,
- void *stbuf)
+/* Return the metadata field element size in bytes */
+static int get_metadata_field_bytes(u64 field_id)
{
- u16 *st_member = stbuf + offset;
+ /*
+ * TDX supports 8/16/32/64 bits metadata field element sizes.
+ * TDX module determines the metadata element size based on the
+ * "element size code" encoded in the field ID (see the comment
+ * of MD_FIELD_ID_ELE_SIZE_CODE macro for specific encodings).
+ */
+ return 1 << MD_FIELD_ID_ELE_SIZE_CODE(field_id);
+}
+
+static int stbuf_read_sys_metadata_field(u64 field_id,
+ int offset,
+ int bytes,
+ void *stbuf)
+{
+ void *st_member = stbuf + offset;
u64 tmp;
int ret;

- if (WARN_ON_ONCE(MD_FIELD_ID_ELE_SIZE_CODE(field_id) !=
- MD_FIELD_ID_ELE_SIZE_16BIT))
+ if (WARN_ON_ONCE(get_metadata_field_bytes(field_id) != bytes))
return -EINVAL;

ret = read_sys_metadata_field(field_id, &tmp);
if (ret)
return ret;

- *st_member = tmp;
+ memcpy(st_member, &tmp, bytes);

return 0;
}
@@ -295,11 +307,30 @@ static int read_sys_metadata_field16(u64 field_id,
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) }
+ .offset = offsetof(_struct, _member), \
+ .size = sizeof(typeof(((_struct *)0)->_member)) }
+
+static int read_sys_metadata(struct field_mapping *fields, int nr_fields,
+ void *stbuf)
+{
+ int i, ret;
+
+ for (i = 0; i < nr_fields; i++) {
+ ret = stbuf_read_sys_metadata_field(fields[i].field_id,
+ fields[i].offset,
+ fields[i].size,
+ stbuf);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}

#define TD_SYSINFO_MAP_TDMR_INFO(_field_id, _member) \
TD_SYSINFO_MAP(_field_id, struct tdx_tdmr_sysinfo, _member)
@@ -314,19 +345,9 @@ static int get_tdx_tdmr_sysinfo(struct tdx_tdmr_sysinfo *tdmr_sysinfo)
TD_SYSINFO_MAP_TDMR_INFO(PAMT_2M_ENTRY_SIZE, pamt_entry_size[TDX_PS_2M]),
TD_SYSINFO_MAP_TDMR_INFO(PAMT_1G_ENTRY_SIZE, pamt_entry_size[TDX_PS_1G]),
};
- int ret;
- int i;

/* Populate 'tdmr_sysinfo' fields using the mapping structure above: */
- for (i = 0; i < ARRAY_SIZE(fields); i++) {
- ret = read_sys_metadata_field16(fields[i].field_id,
- fields[i].offset,
- tdmr_sysinfo);
- if (ret)
- return ret;
- }
-
- return 0;
+ return read_sys_metadata(fields, ARRAY_SIZE(fields), tdmr_sysinfo);
}

/* Calculate the actual TDMR size */
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index b701f69485d3..4c32c8bf156a 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -53,8 +53,6 @@
#define MD_FIELD_ID_ELE_SIZE_CODE(_field_id) \
(((_field_id) & GENMASK_ULL(33, 32)) >> 32)

-#define MD_FIELD_ID_ELE_SIZE_16BIT 1
-
struct tdmr_reserved_area {
u64 offset;
u64 size;
--
2.25.1