| Message ID | f9148e67e968d7aed4707b67ea9b1aa761401255.1685887183.git.kai.huang@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | TDX host kernel support | expand |
On 6/4/23 07:27, Kai Huang wrote: > Constructing the list of TDMRs consists below steps: <grumble> <grumble> grammar <grumble> <grumble> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
On 6/4/23 07:27, Kai Huang wrote: > +struct tdmr_info_list { > + void *tdmrs; /* Flexible array to hold 'tdmr_info's */ > + int nr_consumed_tdmrs; /* How many 'tdmr_info's are in use */ I'm looking back here after seeing the weird cast in the next patch. Why is this a void* instead of a _real_ type?
On Wed, 2023-06-07 at 08:57 -0700, Dave Hansen wrote: > On 6/4/23 07:27, Kai Huang wrote: > > +struct tdmr_info_list { > > + void *tdmrs; /* Flexible array to hold 'tdmr_info's */ > > + int nr_consumed_tdmrs; /* How many 'tdmr_info's are in use */ > > I'm looking back here after seeing the weird cast in the next patch. > > Why is this a void* instead of a _real_ type? I followed your suggestion in v8: https://lore.kernel.org/linux-mm/725de6e9-e468-48ef-3bae-1e8a1b7ef0f7@intel.com/ I quoted the relevant part here: > +/* Get the TDMR from the list at the given index. */ > +static struct tdmr_info *tdmr_entry(struct tdmr_info_list *tdmr_list, > + int idx) > +{ > + return (struct tdmr_info *)((unsigned long)tdmr_list->first_tdmr + > + tdmr_list->tdmr_sz * idx); > +} I think that's more complicated and has more casting than necessary. This looks nicer: int tdmr_info_offset = tdmr_list->tdmr_sz * idx; return (void *)tdmr_list->first_tdmr + tdmr_info_offset; Also, it might even be worth keeping ->first_tdmr as a void*. It isn't a real C array and keeping it as void* would keep anyone from doing: tdmr_foo = tdmr_list->first_tdmr[foo];
On Mon, Jun 05, 2023 at 02:27:23AM +1200, Kai Huang wrote: > @@ -50,6 +51,8 @@ static DEFINE_MUTEX(tdx_module_lock); > /* All TDX-usable memory regions. Protected by mem_hotplug_lock. */ > static LIST_HEAD(tdx_memlist); > > +static struct tdmr_info_list tdx_tdmr_list; > + > /* > * Wrapper of __seamcall() to convert SEAMCALL leaf function error code > * to kernel error code. @seamcall_ret and @out contain the SEAMCALL The name is misleading. It is not list, it is an array. ... > @@ -112,6 +135,15 @@ struct tdx_memblock { > unsigned long end_pfn; > }; > > +struct tdmr_info_list { > + void *tdmrs; /* Flexible array to hold 'tdmr_info's */ > + int nr_consumed_tdmrs; /* How many 'tdmr_info's are in use */ > + > + /* Metadata for finding target 'tdmr_info' and freeing @tdmrs */ > + int tdmr_sz; /* Size of one 'tdmr_info' */ > + int max_tdmrs; /* How many 'tdmr_info's are allocated */ > +}; > + > struct tdx_module_output; > u64 __seamcall(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9, > struct tdx_module_output *out); Otherwise, looks okay. Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
On Fri, 2023-06-09 at 01:52 +0300, kirill.shutemov@linux.intel.com wrote: > On Mon, Jun 05, 2023 at 02:27:23AM +1200, Kai Huang wrote: > > @@ -50,6 +51,8 @@ static DEFINE_MUTEX(tdx_module_lock); > > /* All TDX-usable memory regions. Protected by mem_hotplug_lock. */ > > static LIST_HEAD(tdx_memlist); > > > > +static struct tdmr_info_list tdx_tdmr_list; > > + > > /* > > * Wrapper of __seamcall() to convert SEAMCALL leaf function error code > > * to kernel error code. @seamcall_ret and @out contain the SEAMCALL > > The name is misleading. It is not list, it is an array. I followed Dave's suggestion in v7: https://lore.kernel.org/lkml/d84ad1d2-83f9-dab5-5639-8d71f382e3ff@intel.com/ Quote the relevant part here: " > +static struct tdmr_info *tdmr_array_entry(struct tdmr_info *tdmr_array, > + int idx) > +{ > + return (struct tdmr_info *)((unsigned long)tdmr_array + > + cal_tdmr_size() * idx); > +} FWIW, I think it's probably a bad idea to have 'struct tdmr_info *' types floating around since: tmdr_info_array[0] works, but: tmdr_info_array[1] will blow up in your face. It would almost make sense to have struct tdmr_info_list { struct tdmr_info *first_tdmr; } and then pass around pointers to the 'struct tdmr_info_list'. Maybe that's overkill, but it is kinda silly to call something an array if [] doesn't work on it. " Personally I think it's also fine to use 'list' (e.g., we can also interpret the name from "English language"'s perspective). Hi Dave, Should I change the name to "tdmr_info_array"? > > > ... > > > @@ -112,6 +135,15 @@ struct tdx_memblock { > > unsigned long end_pfn; > > }; > > > > +struct tdmr_info_list { > > + void *tdmrs; /* Flexible array to hold 'tdmr_info's */ > > + int nr_consumed_tdmrs; /* How many 'tdmr_info's are in use */ > > + > > + /* Metadata for finding target 'tdmr_info' and freeing @tdmrs */ > > + int tdmr_sz; /* Size of one 'tdmr_info' */ > > + int max_tdmrs; /* How many 'tdmr_info's are allocated */ > > +}; > > + > > struct tdx_module_output; > > u64 __seamcall(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9, > > struct tdx_module_output *out); > > Otherwise, looks okay. > > Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> >
On 6/11/23 19:21, Huang, Kai wrote:
> Should I change the name to "tdmr_info_array"?
If foo[bar] works on it, then it's an array. If not, then it's not an
array.
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c index 1504023f7f63..7a20c72361e7 100644 --- a/arch/x86/virt/vmx/tdx/tdx.c +++ b/arch/x86/virt/vmx/tdx/tdx.c @@ -24,6 +24,7 @@ #include <linux/minmax.h> #include <linux/sizes.h> #include <linux/pfn.h> +#include <linux/align.h> #include <asm/msr-index.h> #include <asm/msr.h> #include <asm/archrandom.h> @@ -50,6 +51,8 @@ static DEFINE_MUTEX(tdx_module_lock); /* All TDX-usable memory regions. Protected by mem_hotplug_lock. */ static LIST_HEAD(tdx_memlist); +static struct tdmr_info_list tdx_tdmr_list; + /* * Wrapper of __seamcall() to convert SEAMCALL leaf function error code * to kernel error code. @seamcall_ret and @out contain the SEAMCALL @@ -329,6 +332,80 @@ static int build_tdx_memlist(struct list_head *tmb_list) return ret; } +/* Calculate the actual TDMR size */ +static int tdmr_size_single(u16 max_reserved_per_tdmr) +{ + int tdmr_sz; + + /* + * The actual size of TDMR depends on the maximum + * number of reserved areas. + */ + tdmr_sz = sizeof(struct tdmr_info); + tdmr_sz += sizeof(struct tdmr_reserved_area) * max_reserved_per_tdmr; + + return ALIGN(tdmr_sz, TDMR_INFO_ALIGNMENT); +} + +static int alloc_tdmr_list(struct tdmr_info_list *tdmr_list, + struct tdsysinfo_struct *sysinfo) +{ + size_t tdmr_sz, tdmr_array_sz; + void *tdmr_array; + + tdmr_sz = tdmr_size_single(sysinfo->max_reserved_per_tdmr); + tdmr_array_sz = tdmr_sz * sysinfo->max_tdmrs; + + /* + * To keep things simple, allocate all TDMRs together. + * The buffer needs to be physically contiguous to make + * sure each TDMR is physically contiguous. + */ + tdmr_array = alloc_pages_exact(tdmr_array_sz, + GFP_KERNEL | __GFP_ZERO); + if (!tdmr_array) + return -ENOMEM; + + tdmr_list->tdmrs = tdmr_array; + + /* + * Keep the size of TDMR to find the target TDMR + * at a given index in the TDMR list. + */ + tdmr_list->tdmr_sz = tdmr_sz; + tdmr_list->max_tdmrs = sysinfo->max_tdmrs; + tdmr_list->nr_consumed_tdmrs = 0; + + return 0; +} + +static void free_tdmr_list(struct tdmr_info_list *tdmr_list) +{ + free_pages_exact(tdmr_list->tdmrs, + tdmr_list->max_tdmrs * tdmr_list->tdmr_sz); +} + +/* + * Construct a list of TDMRs on the preallocated space in @tdmr_list + * to cover all TDX memory regions in @tmb_list based on the TDX module + * information in @sysinfo. + */ +static int construct_tdmrs(struct list_head *tmb_list, + struct tdmr_info_list *tdmr_list, + struct tdsysinfo_struct *sysinfo) +{ + /* + * TODO: + * + * - Fill out TDMRs to cover all TDX memory regions. + * - Allocate and set up PAMTs for each TDMR. + * - Designate reserved areas for each TDMR. + * + * Return -EINVAL until constructing TDMRs is done + */ + return -EINVAL; +} + static int init_tdx_module(void) { static DECLARE_PADDED_STRUCT(tdsysinfo_struct, tdsysinfo, @@ -358,11 +435,19 @@ static int init_tdx_module(void) if (ret) goto out; + /* Allocate enough space for constructing TDMRs */ + ret = alloc_tdmr_list(&tdx_tdmr_list, sysinfo); + if (ret) + goto out_free_tdx_mem; + + /* Cover all TDX-usable memory regions in TDMRs */ + ret = construct_tdmrs(&tdx_memlist, &tdx_tdmr_list, sysinfo); + if (ret) + goto out_free_tdmrs; + /* * TODO: * - * - Construct a list of "TD Memory Regions" (TDMRs) to cover - * all TDX-usable memory regions. * - Configure the TDMRs and the global KeyID to the TDX module. * - Configure the global KeyID on all packages. * - Initialize all TDMRs. @@ -370,6 +455,12 @@ static int init_tdx_module(void) * Return error before all steps are done. */ ret = -EINVAL; +out_free_tdmrs: + if (ret) + free_tdmr_list(&tdx_tdmr_list); +out_free_tdx_mem: + if (ret) + free_tdx_memlist(&tdx_memlist); out: /* * @tdx_memlist is written here and read at memory hotplug time. diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h index 4b6fc0d8b420..c20848e76469 100644 --- a/arch/x86/virt/vmx/tdx/tdx.h +++ b/arch/x86/virt/vmx/tdx/tdx.h @@ -94,6 +94,29 @@ struct tdsysinfo_struct { DECLARE_FLEX_ARRAY(struct cpuid_config, cpuid_configs); } __packed; +struct tdmr_reserved_area { + u64 offset; + u64 size; +} __packed; + +#define TDMR_INFO_ALIGNMENT 512 + +struct tdmr_info { + u64 base; + u64 size; + u64 pamt_1g_base; + u64 pamt_1g_size; + u64 pamt_2m_base; + u64 pamt_2m_size; + u64 pamt_4k_base; + u64 pamt_4k_size; + /* + * Actual number of reserved areas depends on + * 'struct tdsysinfo_struct'::max_reserved_per_tdmr. + */ + DECLARE_FLEX_ARRAY(struct tdmr_reserved_area, reserved_areas); +} __packed __aligned(TDMR_INFO_ALIGNMENT); + /* * Do not put any hardware-defined TDX structure representations below * this comment! @@ -112,6 +135,15 @@ struct tdx_memblock { unsigned long end_pfn; }; +struct tdmr_info_list { + void *tdmrs; /* Flexible array to hold 'tdmr_info's */ + int nr_consumed_tdmrs; /* How many 'tdmr_info's are in use */ + + /* Metadata for finding target 'tdmr_info' and freeing @tdmrs */ + int tdmr_sz; /* Size of one 'tdmr_info' */ + int max_tdmrs; /* How many 'tdmr_info's are allocated */ +}; + struct tdx_module_output; u64 __seamcall(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9, struct tdx_module_output *out);
After the kernel selects all TDX-usable memory regions, the kernel needs to pass those regions to the TDX module via data structure "TD Memory Region" (TDMR). Add a placeholder to construct a list of TDMRs (in multiple steps) to cover all TDX-usable memory regions. === Long Version === TDX provides increased levels of memory confidentiality and integrity. This requires special hardware support for features like memory encryption and storage of memory integrity checksums. Not all memory satisfies these requirements. As a result, TDX introduced the concept of a "Convertible Memory Region" (CMR). During boot, the firmware builds a list of all of the memory ranges which can provide the TDX security guarantees. The list of these ranges is available to the kernel by querying the TDX module. The TDX architecture needs additional metadata to record things like which TD guest "owns" a given page of memory. This metadata essentially serves as the 'struct page' for the TDX module. The space for this metadata is not reserved by the hardware up front and must be allocated by the kernel and given to the TDX module. Since this metadata consumes space, the VMM can choose whether or not to allocate it for a given area of convertible memory. If it chooses not to, the memory cannot receive TDX protections and can not be used by TDX guests as private memory. For every memory region that the VMM wants to use as TDX memory, it sets up a "TD Memory Region" (TDMR). Each TDMR represents a physically contiguous convertible range and must also have its own physically contiguous metadata table, referred to as a Physical Address Metadata Table (PAMT), to track status for each page in the TDMR range. Unlike a CMR, each TDMR requires 1G granularity and alignment. To support physical RAM areas that don't meet those strict requirements, each TDMR permits a number of internal "reserved areas" which can be placed over memory holes. If PAMT metadata is placed within a TDMR it must be covered by one of these reserved areas. Let's summarize the concepts: CMR - Firmware-enumerated physical ranges that support TDX. CMRs are 4K aligned. TDMR - Physical address range which is chosen by the kernel to support TDX. 1G granularity and alignment required. Each TDMR has reserved areas where TDX memory holes and overlapping PAMTs can be represented. PAMT - Physically contiguous TDX metadata. One table for each page size per TDMR. Roughly 1/256th of TDMR in size. 256G TDMR = ~1G PAMT. As one step of initializing the TDX module, the kernel configures TDX-usable memory regions by passing a list of TDMRs to the TDX module. Constructing the list of TDMRs consists below steps: 1) Fill out TDMRs to cover all memory regions that the TDX module will use for TD memory. 2) Allocate and set up PAMT for each TDMR. 3) Designate reserved areas for each TDMR. Add a placeholder to construct TDMRs to do the above steps. To keep things simple, just allocate enough space to hold maximum number of TDMRs up front. Keep the TDMRs if module initialization is successful. A later patch will need to use them to find PAMTs after module initialization. Signed-off-by: Kai Huang <kai.huang@intel.com> Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com> --- v10 -> v11: - Changed to keep TDMRs after module initialization to deal with TDX erratum in future patches. v9 -> v10: - Changed the TDMR list from static variable back to local variable as now TDX module isn't disabled when tdx_cpu_enable() fails. v8 -> v9: - Changes around 'struct tdmr_info_list' (Dave): - Moved the declaration from tdx.c to tdx.h. - Renamed 'first_tdmr' to 'tdmrs'. - 'nr_tdmrs' -> 'nr_consumed_tdmrs'. - Changed 'tdmrs' to 'void *'. - Improved comments for all structure members. - Added a missing empty line in alloc_tdmr_list() (Dave). v7 -> v8: - Improved changelog to tell this is one step of "TODO list" in init_tdx_module(). - Other changelog improvement suggested by Dave (with "Create TDMRs" to "Fill out TDMRs" to align with the code). - Added a "TODO list" comment to lay out the steps to construct TDMRs, following the same idea of "TODO list" in tdx_module_init(). - Introduced 'struct tdmr_info_list' (Dave) - Further added additional members (tdmr_sz/max_tdmrs/nr_tdmrs) to simplify getting TDMR by given index, and reduce passing arguments around functions. - Added alloc_tdmr_list()/free_tdmr_list() accordingly, which internally uses tdmr_size_single() (Dave). - tdmr_num -> nr_tdmrs (Dave). v6 -> v7: - Improved commit message to explain 'int' overflow cannot happen in cal_tdmr_size() and alloc_tdmr_array(). -- Andy/Dave. v5 -> v6: - construct_tdmrs_memblock() -> construct_tdmrs() as 'tdx_memblock' is used instead of memblock. - Added Isaku's Reviewed-by. - v3 -> v5 (no feedback on v4): - Moved calculating TDMR size to this patch. - Changed to use alloc_pages_exact() to allocate buffer for all TDMRs once, instead of allocating each TDMR individually. - Removed "crypto protection" in the changelog. - -EFAULT -> -EINVAL in couple of places. --- arch/x86/virt/vmx/tdx/tdx.c | 95 ++++++++++++++++++++++++++++++++++++- arch/x86/virt/vmx/tdx/tdx.h | 32 +++++++++++++ 2 files changed, 125 insertions(+), 2 deletions(-)