[PATCH v12 08/22] x86/virt/tdx: Get information about TDX module and TDX-capable memory
From: Kai Huang
Date: Mon Jun 26 2023 - 10:15:21 EST
Start to transit out the "multi-steps" to initialize the TDX module.
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.
CMRs tell the kernel which memory is TDX compatible. The kernel takes
CMRs (plus a little more metadata) and constructs "TD Memory Regions"
(TDMRs). TDMRs let the kernel grant TDX protections to some or all of
the CMR areas.
The TDX module also reports necessary information to let the kernel
build TDMRs and run TDX guests in structure 'tdsysinfo_struct'. The
list of CMRs, along with the TDX module information, is available to
the kernel by querying the TDX module.
As a preparation to construct TDMRs, get the TDX module information and
the list of CMRs. Print out CMRs to help user to decode which memory
regions are TDX convertible.
The 'tdsysinfo_struct' is fairly large (1024 bytes) and contains a lot
of info about the TDX module. Fully define the entire structure, but
only use the fields necessary to build the TDMRs and pr_info() some
basics about the module. The rest of the fields will get used by KVM.
Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
Reviewed-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
v11 -> v12:
- Changed to use dynamic allocation for TDSYSINFO_STRUCT and CMR array
(Kirill).
- Keep SEAMCALL leaf macro definitions in order (Kirill)
- Removed is_cmr_empty() but open code directly (David)
- 'atribute' -> 'attribute' (David)
v10 -> v11:
- No change.
v9 -> v10:
- Added back "start to transit out..." as now per-cpu init has been
moved out from tdx_enable().
v8 -> v9:
- Removed "start to trransit out ..." part in changelog since this patch
is no longer the first step anymore.
- Changed to declare 'tdsysinfo' and 'cmr_array' as local static, and
changed changelog accordingly (Dave).
- Improved changelog to explain why to declare 'tdsysinfo_struct' in
full but only use a few members of them (Dave).
v7 -> v8: (Dave)
- Improved changelog to tell this is the first patch to transit out the
"multi-steps" init_tdx_module().
- Removed all CMR check/trim code but to depend on later SEAMCALL.
- Variable 'vertical alignment' in print TDX module information.
- Added DECLARE_PADDED_STRUCT() for padded structure.
- Made tdx_sysinfo and tdx_cmr_array[] to be function local variable
(and rename them accordingly), and added -Wframe-larger-than=4096 flag
to silence the build warning.
v6 -> v7:
- Simplified the check of CMRs due to the fact that TDX actually
verifies CMRs (that are passed by the BIOS) before enabling TDX.
- Changed the function name from check_cmrs() -> trim_empty_cmrs().
- Added CMR page aligned check so that later patch can just get the PFN
using ">> PAGE_SHIFT".
v5 -> v6:
- Added to also print TDX module's attribute (Isaku).
- Removed all arguments in tdx_gete_sysinfo() to use static variables
of 'tdx_sysinfo' and 'tdx_cmr_array' directly as they are all used
directly in other functions in later patches.
- Added Isaku's Reviewed-by.
- v3 -> v5 (no feedback on v4):
- Renamed sanitize_cmrs() to check_cmrs().
- Removed unnecessary sanity check against tdx_sysinfo and tdx_cmr_array
actual size returned by TDH.SYS.INFO.
- Changed -EFAULT to -EINVAL in couple places.
- Added comments around tdx_sysinfo and tdx_cmr_array saying they are
used by TDH.SYS.INFO ABI.
- Changed to pass 'tdx_sysinfo' and 'tdx_cmr_array' as function
arguments in tdx_get_sysinfo().
- Changed to only print BIOS-CMR when check_cmrs() fails.
---
arch/x86/virt/vmx/tdx/tdx.c | 79 ++++++++++++++++++++++++++++++++++++-
arch/x86/virt/vmx/tdx/tdx.h | 60 ++++++++++++++++++++++++++++
2 files changed, 137 insertions(+), 2 deletions(-)
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 29ca18f66d61..a2129cbe056e 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -20,6 +20,7 @@
#include <asm/msr-index.h>
#include <asm/msr.h>
#include <asm/archrandom.h>
+#include <asm/page.h>
#include <asm/tdx.h>
#include "tdx.h"
@@ -159,12 +160,79 @@ int tdx_cpu_enable(void)
}
EXPORT_SYMBOL_GPL(tdx_cpu_enable);
+static void print_cmrs(struct cmr_info *cmr_array, int nr_cmrs)
+{
+ int i;
+
+ for (i = 0; i < nr_cmrs; i++) {
+ struct cmr_info *cmr = &cmr_array[i];
+
+ /*
+ * The array of CMRs reported via TDH.SYS.INFO can
+ * contain tail empty CMRs. Don't print them.
+ */
+ if (!cmr->size)
+ break;
+
+ pr_info("CMR: [0x%llx, 0x%llx)\n", cmr->base,
+ cmr->base + cmr->size);
+ }
+}
+
+static int tdx_get_sysinfo(struct tdsysinfo_struct *sysinfo,
+ struct cmr_info *cmr_array)
+{
+ struct tdx_module_output out;
+ u64 sysinfo_pa, cmr_array_pa;
+ int ret;
+
+ sysinfo_pa = __pa(sysinfo);
+ cmr_array_pa = __pa(cmr_array);
+ ret = seamcall(TDH_SYS_INFO, sysinfo_pa, TDSYSINFO_STRUCT_SIZE,
+ cmr_array_pa, MAX_CMRS, NULL, &out);
+ if (ret)
+ return ret;
+
+ pr_info("TDX module: attributes 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,
+ sysinfo->build_date, sysinfo->build_num);
+
+ /* R9 contains the actual entries written to the CMR array. */
+ print_cmrs(cmr_array, out.r9);
+
+ return 0;
+}
+
static int init_tdx_module(void)
{
+ struct tdsysinfo_struct *sysinfo;
+ struct cmr_info *cmr_array;
+ int ret;
+
+ /*
+ * Get the TDSYSINFO_STRUCT and CMRs from the TDX module.
+ *
+ * The buffers of the TDSYSINFO_STRUCT and the CMR array passed
+ * to the TDX module must be 1024-bytes and 512-bytes aligned
+ * respectively. Allocate one page to accommodate them both and
+ * also meet those alignment requirements.
+ */
+ sysinfo = (struct tdsysinfo_struct *)__get_free_page(GFP_KERNEL);
+ if (!sysinfo)
+ return -ENOMEM;
+ cmr_array = (struct cmr_info *)((unsigned long)sysinfo + PAGE_SIZE / 2);
+
+ BUILD_BUG_ON(PAGE_SIZE / 2 < TDSYSINFO_STRUCT_SIZE);
+ BUILD_BUG_ON(PAGE_SIZE / 2 < sizeof(struct cmr_info) * MAX_CMRS);
+
+ ret = tdx_get_sysinfo(sysinfo, cmr_array);
+ if (ret)
+ goto out;
+
/*
* TODO:
*
- * - Get TDX module information and TDX-capable memory regions.
* - Build the list of TDX-usable memory regions.
* - Construct a list of "TD Memory Regions" (TDMRs) to cover
* all TDX-usable memory regions.
@@ -174,7 +242,14 @@ static int init_tdx_module(void)
*
* Return error before all steps are done.
*/
- return -EINVAL;
+ ret = -EINVAL;
+out:
+ /*
+ * For now both @sysinfo and @cmr_array are only used during
+ * module initialization, so always free them.
+ */
+ free_page((unsigned long)sysinfo);
+ return ret;
}
static int __tdx_enable(void)
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index 9fb46033c852..8ab2d40971ea 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -3,6 +3,8 @@
#define _X86_VIRT_TDX_H
#include <linux/types.h>
+#include <linux/stddef.h>
+#include <linux/compiler_attributes.h>
/*
* This file contains both macros and data structures defined by the TDX
@@ -19,9 +21,67 @@
/*
* TDX module SEAMCALL leaf functions
*/
+#define TDH_SYS_INFO 32
#define TDH_SYS_INIT 33
#define TDH_SYS_LP_INIT 35
+struct cmr_info {
+ u64 base;
+ u64 size;
+} __packed;
+
+#define MAX_CMRS 32
+
+struct cpuid_config {
+ u32 leaf;
+ u32 sub_leaf;
+ u32 eax;
+ u32 ebx;
+ u32 ecx;
+ u32 edx;
+} __packed;
+
+#define TDSYSINFO_STRUCT_SIZE 1024
+
+/*
+ * The size of this structure itself is flexible. The actual structure
+ * passed to TDH.SYS.INFO must be padded to 1024 bytes and be 1204-bytes
+ * aligned.
+ */
+struct tdsysinfo_struct {
+ /* TDX-SEAM Module Info */
+ u32 attributes;
+ u32 vendor_id;
+ u32 build_date;
+ u16 build_num;
+ u16 minor_version;
+ u16 major_version;
+ u8 reserved0[14];
+ /* Memory Info */
+ u16 max_tdmrs;
+ u16 max_reserved_per_tdmr;
+ u16 pamt_entry_size;
+ u8 reserved1[10];
+ /* Control Struct Info */
+ u16 tdcs_base_size;
+ u8 reserved2[2];
+ u16 tdvps_base_size;
+ u8 tdvps_xfam_dependent_size;
+ u8 reserved3[9];
+ /* TD Capabilities */
+ u64 attributes_fixed0;
+ u64 attributes_fixed1;
+ u64 xfam_fixed0;
+ u64 xfam_fixed1;
+ u8 reserved4[32];
+ u32 num_cpuid_config;
+ /*
+ * The actual number of CPUID_CONFIG depends on above
+ * 'num_cpuid_config'.
+ */
+ DECLARE_FLEX_ARRAY(struct cpuid_config, cpuid_configs);
+} __packed;
+
/*
* Do not put any hardware-defined TDX structure representations below
* this comment!
--
2.40.1