arch/x86: support slaunch with AMD SKINIT

This mostly involves not running Intel-specific code when on AMD. There are only a few new AMD-specific implementation details: - finding SLB start and size and then mapping and protecting it - managing offset for adding the next TPM log entry (TXT-compatible data prepared by SKL is stored inside of vendor data field of TCG header) Signed-off-by: Sergii Dmytruk <[email protected]> Signed-off-by: Krystian Hebel <[email protected]>
TrenchBoot · Nov 8, 2024 · 31fca18 · 31fca18
1 parent 597b92e
commit 31fca18
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Showing 4 changed files with 122 additions and 16 deletions.
diff --git a/xen/arch/x86/e820.c b/xen/arch/x86/e820.c
@@ -457,7 +457,7 @@ static uint64_t __init mtrr_top_of_ram(void)
     rdmsrl(MSR_MTRRcap, mtrr_cap);
     rdmsrl(MSR_MTRRdefType, mtrr_def);
 
-    if ( slaunch_active )
+    if ( slaunch_active && boot_cpu_data.x86_vendor == X86_VENDOR_INTEL )
         txt_restore_mtrrs(e820_verbose);
 
     if ( e820_verbose )

diff --git a/xen/arch/x86/include/asm/slaunch.h b/xen/arch/x86/include/asm/slaunch.h
@@ -11,6 +11,8 @@
 /*
  * Secure Launch event log entry types. The TXT specification defines the
  * base event value as 0x400 for DRTM values.
+ *
+ * Using the same values for AMD SKINIT.
  */
 #define TXT_EVTYPE_BASE            0x400
 #define DLE_EVTYPE_SLAUNCH         (TXT_EVTYPE_BASE + 0x102)

diff --git a/xen/arch/x86/slaunch.c b/xen/arch/x86/slaunch.c
@@ -9,6 +9,10 @@
 #include <xen/mm.h>
 #include <asm/bootinfo.h>
 
+/* SLB is 64k, 64k-aligned */
+#define SKINIT_SLB_SIZE  0x10000
+#define SKINIT_SLB_ALIGN 0x10000
+
 bool __initdata slaunch_active;
 uint32_t __initdata slaunch_slrt;
 
@@ -37,6 +41,19 @@ int __init map_l2(unsigned long paddr, unsigned long size)
                             pages, PAGE_HYPERVISOR);
 }
 
+static uint32_t get_slb_start(void)
+{
+    /* The runtime computation relies on size being a power of 2 and equal to
+     * alignment. Make sure these assumptions hold. */
+    BUILD_BUG_ON(SKINIT_SLB_SIZE != SKINIT_SLB_ALIGN);
+    BUILD_BUG_ON(SKINIT_SLB_SIZE == 0);
+    BUILD_BUG_ON((SKINIT_SLB_SIZE & (SKINIT_SLB_SIZE - 1)) != 0);
+
+    /* Rounding any address within SLB down to alignment gives SLB base and
+     * SLRT is inside SLB on AMD. */
+    return slaunch_slrt & ~(SKINIT_SLB_SIZE - 1);
+}
+
 void __init map_slaunch_mem_regions(void)
 {
     void *evt_log_addr;
@@ -45,7 +62,14 @@ void __init map_slaunch_mem_regions(void)
     map_l2(TPM_TIS_BASE, TPM_TIS_SIZE);
 
     /* Vendor-specific part. It may include contain slaunch_slrt. */
-    map_txt_mem_regions();
+    if ( boot_cpu_data.x86_vendor == X86_VENDOR_INTEL )
+    {
+        map_txt_mem_regions();
+    }
+    else if ( boot_cpu_data.x86_vendor == X86_VENDOR_AMD )
+    {
+        map_l2(get_slb_start(), SKINIT_SLB_SIZE);
+    }
 
     find_evt_log(__va(slaunch_slrt), &evt_log_addr, &evt_log_size);
     if ( evt_log_addr != NULL )
@@ -71,11 +95,25 @@ void __init protect_slaunch_mem_regions(void)
     }
 
     /* Vendor-specific part. */
-    protect_txt_mem_regions();
+    if ( boot_cpu_data.x86_vendor == X86_VENDOR_INTEL )
+    {
+        protect_txt_mem_regions();
+    }
+    else if ( boot_cpu_data.x86_vendor == X86_VENDOR_AMD )
+    {
+        uint64_t slb_start = get_slb_start();
+        uint64_t slb_end = slb_start + SKINIT_SLB_SIZE;
+        printk("SLAUNCH: reserving SLB (%#lx - %#lx)\n", slb_start, slb_end);
+        e820_change_range_type(&e820_raw, slb_start, slb_end,
+                               E820_RAM, E820_RESERVED);
+    }
 }
 
 static struct slr_table *slr_get_table(void)
 {
+    bool intel_cpu = (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL);
+    uint16_t slrt_architecture = intel_cpu ? SLR_INTEL_TXT : SLR_AMD_SKINIT;
+
     struct slr_table *slrt = __va(slaunch_slrt);
 
     map_l2(slaunch_slrt, PAGE_SIZE);
@@ -85,9 +123,9 @@ static struct slr_table *slr_get_table(void)
     /* XXX: are newer revisions allowed? */
     if ( slrt->revision != SLR_TABLE_REVISION )
         panic("SLRT is of unsupported revision: %#04x!\n", slrt->revision);
-    if ( slrt->architecture != SLR_INTEL_TXT )
-        panic("SLRT is for unexpected architecture: %#04x!\n",
-              slrt->architecture);
+    if ( slrt->architecture != slrt_architecture )
+        panic("SLRT is for unexpected architecture: %#04x != %#04x!\n",
+              slrt->architecture, slrt_architecture);
     if ( slrt->size > slrt->max_size )
         panic("SLRT is larger than its max size: %#08x > %#08x!\n",
               slrt->size, slrt->max_size);
@@ -104,14 +142,18 @@ void tpm_measure_slrt(void)
 
     if ( slrt->revision == 1 )
     {
-        /* In revision one of the SLRT, only Intel info table is measured. */
-        struct slr_entry_intel_info *intel_info =
-            (void *)slr_next_entry_by_tag(slrt, NULL, SLR_ENTRY_INTEL_INFO);
-        if ( intel_info == NULL )
-            panic("SLRT is missing Intel-specific information!\n");
-
-        tpm_hash_extend(DRTM_LOC, DRTM_DATA_PCR, (uint8_t *)intel_info,
-                        sizeof(*intel_info), DLE_EVTYPE_SLAUNCH, NULL, 0);
+        if ( boot_cpu_data.x86_vendor == X86_VENDOR_INTEL )
+        {
+            /* In revision one of the SLRT, only Intel info table is
+             * measured. */
+            struct slr_entry_intel_info *intel_info =
+                (void *)slr_next_entry_by_tag(slrt, NULL, SLR_ENTRY_INTEL_INFO);
+            if ( intel_info == NULL )
+                panic("SLRT is missing Intel-specific information!\n");
+
+            tpm_hash_extend(DRTM_LOC, DRTM_DATA_PCR, (uint8_t *)intel_info,
+                            sizeof(*intel_info), DLE_EVTYPE_SLAUNCH, NULL, 0);
+        }
     }
     else
     {

diff --git a/xen/arch/x86/tpm.c b/xen/arch/x86/tpm.c
@@ -21,6 +21,7 @@
 #include <asm/intel_txt.h>
 #include <asm/slaunch.h>
 #include <asm/tpm.h>
+#include <asm/x86-vendors.h>
 
 #ifdef __EARLY_TPM__
 
@@ -57,11 +58,31 @@ void *memcpy(void *dest, const void *src, size_t n)
     return dest;
 }
 
+static bool is_amd_cpu(void)
+{
+    /*
+     * asm/processor.h can't be included in early code, which means neither
+     * cpuid() function nor boot_cpu_data can be used here.
+     */
+    uint32_t eax, ebx, ecx, edx;
+    asm volatile ( "cpuid"
+          : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
+          : "0" (0), "c" (0) );
+    return ebx == X86_VENDOR_AMD_EBX
+        && ecx == X86_VENDOR_AMD_ECX
+        && edx == X86_VENDOR_AMD_EDX;
+}
+
 #else   /* __EARLY_TPM__ */
 
 #include <xen/mm.h>
 #include <xen/pfn.h>
 
+static bool is_amd_cpu(void)
+{
+    return boot_cpu_data.x86_vendor == X86_VENDOR_AMD;
+}
+
 #endif  /* __EARLY_TPM__ */
 
 #define TPM_LOC_REG(loc, reg)   (0x1000 * (loc) + (reg))
@@ -247,6 +268,21 @@ struct TPM12_PCREvent {
     uint8_t Data[];
 };
 
+struct tpm1_spec_id_event {
+    uint32_t pcrIndex;
+    uint32_t eventType;
+    uint8_t digest[20];
+    uint32_t eventSize;
+    uint8_t signature[16];
+    uint32_t platformClass;
+    uint8_t specVersionMinor;
+    uint8_t specVersionMajor;
+    uint8_t specErrata;
+    uint8_t uintnSize;
+    uint8_t vendorInfoSize;
+    uint8_t vendorInfo[0];  /* variable number of members */
+} __packed;
+
 struct txt_ev_log_container_12 {
     char        Signature[20];      /* "TXT Event Container", null-terminated */
     uint8_t     Reserved[12];
@@ -389,6 +425,15 @@ static void *create_log_event12(struct txt_ev_log_container_12 *evt_log,
 {
     struct TPM12_PCREvent *new_entry;
 
+    if ( is_amd_cpu() ) {
+        /*
+         * On AMD, TXT-compatible structure is stored as vendor data of
+         * TCG-defined event log header.
+         */
+        struct tpm1_spec_id_event *spec_id = (void *)evt_log;
+        evt_log = (struct txt_ev_log_container_12 *)&spec_id->vendorInfo[0];
+    }
+
     new_entry = (void *)(((uint8_t *)evt_log) + evt_log->NextEventOffset);
 
     /*
@@ -824,11 +869,28 @@ static uint32_t tpm2_hash_extend(unsigned loc, uint8_t *buf, unsigned size,
 
 #endif /* __EARLY_TPM__ */
 
-static struct heap_event_log_pointer_element2_1 *find_evt_log_ext_data(void)
+static struct heap_event_log_pointer_element2_1 *
+find_evt_log_ext_data(struct tpm2_spec_id_event *evt_log)
 {
     struct txt_os_sinit_data *os_sinit;
     struct txt_ext_data_element *ext_data;
 
+    if ( is_amd_cpu() ) {
+        /*
+         * Event log pointer is defined by TXT specification, but
+         * secure-kernel-loader provides a compatible structure in vendor data
+         * of the log.
+         */
+        const uint8_t *data_size =
+            (void *)&evt_log->digestSizes[evt_log->digestCount];
+
+        if ( *data_size != sizeof(struct heap_event_log_pointer_element2_1) )
+            return NULL;
+
+        /* Vendor data directly follows one-byte size. */
+        return (void *)(data_size + 1);
+    }
+
     os_sinit = txt_os_sinit_data_start(__va(read_txt_reg(TXTCR_HEAP_BASE)));
     ext_data = (void *)((uint8_t *)os_sinit + sizeof(*os_sinit));
 
@@ -861,7 +923,7 @@ create_log_event20(struct tpm2_spec_id_event *evt_log, uint32_t evt_log_size,
     unsigned i;
     uint8_t *p;
 
-    log_ext_data = find_evt_log_ext_data();
+    log_ext_data = find_evt_log_ext_data(evt_log);
     if ( log_ext_data == NULL )
         return log_hashes;