Messages in this thread Patch in this message | | | Date | Wed, 13 Mar 2024 11:44:08 +0800 | Subject | Re: [PATCH 5/5] x86/virt/tdx: Export global metadata read infrastructure | From | Xiaoyao Li <> |
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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@intel.com> > Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > --- > 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 */
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