x86/boot: introduce slaunch_slrt global variable

It holds physical address of SLRT. The value is produced by
slaunch_early (known as txt_early previously), gets set in assembly and
then used by the main C code which don't need to know how we got
it (which is different for different CPUs).

This change additionally renames txt_early.c into slaunch_early.c

Signed-off-by: Sergii Dmytruk <[email protected]>
Signed-off-by: Krystian Hebel <[email protected]>

Author: SergiiDmytruk

xen/arch/x86/boot/Makefile

@@ -2,7 +2,7 @@ obj-bin-y += head.o
 
 obj32 := cmdline.32.o
 obj32 += reloc.32.o
-obj32 += txt_early.32.o
+obj32 += slaunch_early.32.o
 obj32 += tpm_early.32.o
 
 nocov-y   += $(obj32)

xen/arch/x86/boot/head.S

@@ -486,20 +486,34 @@ __start:
         jmp     trampoline_bios_setup
 
 .Lslaunch_proto:
+        /* Upon reaching here, CPU state mostly matches the one setup by the
+         * bootloader with ESP, ESI and EDX being clobbered above. */
+
         /* Save information that TrenchBoot slaunch was used. */
         movb    $1, sym_esi(slaunch_active)
 
+        /* Prepare space for output parameter of slaunch_early_tests(), which is
+         * a structure of two uint32_t fields. */
+        sub     $8, %esp
+
+        push    %esp                             /* pointer to output structure */
         lea     sym_offs(__2M_rwdata_end), %ecx  /* end of target image */
         lea     sym_offs(_start), %edx           /* target base address */
         mov     %esi, %eax                       /* load base address */
-        /* txt_early_tests(load/eax, tgt/edx, tgt_end/ecx) using fastcall. */
-        call    txt_early_tests
+        /* slaunch_early_tests(load/eax, tgt/edx, tgt_end/ecx, ret/stk) using fastcall. */
+        call    slaunch_early_tests
 
-        /*
-         * txt_early_tests() returns MBI address, pass it to tpm_extend_mbi()
-         * and store for later in EBX.
-         */
-        movl    %eax, %ebx
+        /* Move outputs of slaunch_early_tests() from stack into registers. */
+        pop     %eax  /* physical MBI address */
+        pop     %edx  /* physical SLRT address */
+
+        /* Save physical address of SLRT for C code. */
+        mov     %edx, sym_esi(slaunch_slrt)
+
+        /* Store MBI address in EBX where MB2 code expects it. */
+        mov     %eax, %ebx
+
+        /* tpm_extend_mbi(mbi/eax, slrt/edx) using fastcall. */
         call    tpm_extend_mbi
 
         /* Move magic number expected by Multiboot 2 to EAX and fall through. */
@@ -845,9 +859,9 @@ FUNC_LOCAL(reloc)
         .incbin "reloc.bin"
 END(reloc)
 
-FUNC_LOCAL(txt_early_tests)
-        .incbin "txt_early.bin"
-END(txt_early_tests)
+FUNC_LOCAL(slaunch_early_tests)
+        .incbin "slaunch_early.bin"
+END(slaunch_early_tests)
 
 FUNC_LOCAL(tpm_extend_mbi)
         .incbin "tpm_early.bin"

xen/arch/x86/boot/txt_early.c renamed to xen/arch/x86/boot/slaunch_early.c

@@ -17,23 +17,28 @@
 
 /*
  * This entry point is entered from xen/arch/x86/boot/head.S with:
- * - %eax    = load_base_addr,
- * - %edx    = tgt_base_addr,
- * - %ecx    = tgt_end_addr.
- *
- * A pointer to MBI is returned in %eax.
+ * - %eax       = load_base_addr,
+ * - %edx       = tgt_base_addr,
+ * - %ecx       = tgt_end_addr,
+ * - 0x04(%esp) = &result.
  */
 asm (
     "    .text                         \n"
     "    .globl _start                 \n"
     "_start:                           \n"
-    "    jmp  txt_early_tests          \n"
+    "    jmp  slaunch_early_tests      \n"
     );
 
 #include <xen/macros.h>
 #include <xen/types.h>
 #include <asm/intel_txt.h>
 
+struct early_tests_results
+{
+    uint32_t mbi_pa;
+    uint32_t slrt_pa;
+} __packed;
+
 static void verify_pmr_ranges(struct txt_os_mle_data *os_mle,
                               struct txt_os_sinit_data *os_sinit,
                               uint32_t load_base_addr, uint32_t tgt_base_addr,
@@ -110,9 +115,10 @@ static void verify_pmr_ranges(struct txt_os_mle_data *os_mle,
     */
 }
 
-uint32_t txt_early_tests(uint32_t load_base_addr,
+void slaunch_early_tests(uint32_t load_base_addr,
                          uint32_t tgt_base_addr,
-                         uint32_t tgt_end_addr)
+                         uint32_t tgt_end_addr,
+                         struct early_tests_results *result)
 {
     void *txt_heap;
     struct txt_os_mle_data *os_mle;
@@ -133,5 +139,6 @@ uint32_t txt_early_tests(uint32_t load_base_addr,
 
     verify_pmr_ranges(os_mle, os_sinit, load_base_addr, tgt_base_addr, size);
 
-    return os_mle->boot_params_addr;
+    result->mbi_pa = os_mle->boot_params_addr;
+    result->slrt_pa = os_mle->slrt;
 }

xen/arch/x86/include/asm/intel_txt.h

@@ -330,14 +330,6 @@ static inline int is_in_pmr(struct txt_os_sinit_data *os_sinit, uint64_t base,
     return 0;
 }
 
-/* Returns physical address. */
-static inline uint32_t txt_find_slrt(void)
-{
-    struct txt_os_mle_data *os_mle =
-        txt_os_mle_data_start(_txt(read_txt_reg(TXTCR_HEAP_BASE)));
-    return os_mle->slrt;
-}
-
 extern void map_txt_mem_regions(void);
 extern void protect_txt_mem_regions(void);
 extern void txt_restore_mtrrs(bool e820_verbose);

xen/arch/x86/include/asm/slaunch.h

@@ -18,6 +18,7 @@
 #define DLE_EVTYPE_SLAUNCH_END     (TXT_EVTYPE_BASE + 0x104)
 
 extern bool slaunch_active;
+extern uint32_t slaunch_slrt; /* physical address */
 
 /* evt_log is a physical address and the caller must map it to virtual, if
  * needed. */

xen/arch/x86/intel_txt.c

@@ -29,7 +29,7 @@ void __init map_txt_mem_regions(void)
 
     map_l2(txt_heap_base, txt_heap_size);
 
-    find_evt_log(__va(txt_find_slrt()), &evt_log_addr, &evt_log_size);
+    find_evt_log(__va(slaunch_slrt), &evt_log_addr, &evt_log_size);
     map_l2((unsigned long)evt_log_addr, evt_log_size);
     if ( evt_log_addr != NULL )
         map_l2((unsigned long)evt_log_addr, evt_log_size);
@@ -53,7 +53,7 @@ void __init protect_txt_mem_regions(void)
     BUG_ON(rc == 0);
 
     /* TXT TPM Event Log */
-    find_evt_log(__va(txt_find_slrt()), &evt_log_addr, &evt_log_size);
+    find_evt_log(__va(slaunch_slrt), &evt_log_addr, &evt_log_size);
     if ( evt_log_addr != NULL ) {
         printk("SLAUNCH: reserving event log (%#lx - %#lx)\n",
                (uint64_t)evt_log_addr,

xen/arch/x86/slaunch.c

@@ -1,5 +1,4 @@
 #include <xen/types.h>
-#include <asm/intel_txt.h>
 #include <asm/page.h>
 #include <asm/processor.h>
 #include <asm/slaunch.h>
@@ -9,6 +8,7 @@
 #include <xen/multiboot.h>
 
 bool __initdata slaunch_active;
+uint32_t __initdata slaunch_slrt;
 
 static void __maybe_unused compile_time_checks(void)
 {
@@ -37,10 +37,9 @@ int __init map_l2(unsigned long paddr, unsigned long size)
 
 static struct slr_table *slr_get_table(void)
 {
-    uint32_t slrt_pa = txt_find_slrt();
-    struct slr_table *slrt = __va(slrt_pa);
+    struct slr_table *slrt = __va(slaunch_slrt);
 
-    map_l2(slrt_pa, PAGE_SIZE);
+    map_l2(slaunch_slrt, PAGE_SIZE);
 
     if ( slrt->magic != SLR_TABLE_MAGIC )
         panic("SLRT has invalid magic value: %#08x!\n", slrt->magic);
@@ -55,7 +54,7 @@ static struct slr_table *slr_get_table(void)
               slrt->size, slrt->max_size);
 
     if ( slrt->size > PAGE_SIZE )
-        map_l2(slrt_pa, slrt->size);
+        map_l2(slaunch_slrt, slrt->size);
 
     return slrt;
 }

xen/arch/x86/tpm.c

@@ -24,8 +24,9 @@
 
 #ifdef __EARLY_TPM__
 /*
- * This entry point is entered from xen/arch/x86/boot/head.S with MBI base at
- * %eax.
+ * This entry point is entered from xen/arch/x86/boot/head.S with:
+ * - %eax = &mbi,
+ * - %edx = slrt_pa.
  */
 asm (
     "    .text                         \n"
@@ -40,6 +41,8 @@ asm (
 
 #define __va(x)     _p(x)
 
+uint32_t slaunch_slrt;
+
 /*
  * The code is being compiled as a standalone binary without linking to any
  * other part of Xen.  Providing implementation of builtin functions in this
@@ -933,9 +936,7 @@ void tpm_hash_extend(unsigned loc, unsigned pcr, uint8_t *buf, unsigned size,
     void *evt_log_addr;
     uint32_t evt_log_size;
 
-    struct slr_table *slrt = __va(txt_find_slrt());
-
-    find_evt_log(slrt, &evt_log_addr, &evt_log_size);
+    find_evt_log(__va(slaunch_slrt), &evt_log_addr, &evt_log_size);
     evt_log_addr = __va((uintptr_t)evt_log_addr);
 
     if ( is_tpm12() ) {
@@ -973,8 +974,12 @@ void tpm_hash_extend(unsigned loc, unsigned pcr, uint8_t *buf, unsigned size,
 }
 
 #ifdef __EARLY_TPM__
-void tpm_extend_mbi(uint32_t *mbi)
+void tpm_extend_mbi(uint32_t *mbi, uint32_t slrt_pa)
 {
+    /* Early TPM code isn't linked with the rest but still needs to have this
+     * variable with correct value. */
+    slaunch_slrt = slrt_pa;
+
     /* MBI starts with uint32_t total_size. */
     tpm_hash_extend(DRTM_LOC, DRTM_DATA_PCR, (uint8_t *)mbi, *mbi,
                     DLE_EVTYPE_SLAUNCH, NULL, 0);