[PATCH v2 3/3] hvmloader/tests: Introduce WRFSBASE test

[Andrew Cooper <andrew.cooper3@citrix.com>]

Without the bugfix in c/s a1ac4cf52 "x86/cpu: undo BIOS CPUID max_leaf limit
before querying for features", the first move to cr4 may fail despite the
feature being advertised.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Keir Fraser <keir@xen.org>
CC: Jan Beulich <JBeulich@suse.com>
CC: Tim Deegan <tim@xen.org>
CC: Ian Campbell <Ian.Campbell@citrix.com>
CC: Ian Jackson <Ian.Jackson@eu.citrix.com>

---
v2: Drop spurious whitespace change.  Rebase on top of changes to shadow_gs_test()
---
 tools/firmware/hvmloader/tests.c |   67 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/tools/firmware/hvmloader/tests.c b/tools/firmware/hvmloader/tests.c
index 931ed2f..0e70032 100644
--- a/tools/firmware/hvmloader/tests.c
+++ b/tools/firmware/hvmloader/tests.c
@@ -194,6 +194,72 @@ static int shadow_gs_test(void)
     return (ebx == 2) ? TEST_PASS : TEST_FAIL;
 }
 
+static int wrfsbase_test(void)
+{
+    uint64_t *pd = (uint64_t *)PD_START;
+    uint32_t i, eax, ebx, ecx, edx, dummy;
+
+    /* Skip this test if the CPU does not support long mode. */
+    cpuid(0x80000000, &eax, &ebx, &ecx, &edx);
+    if ( eax < 0x80000001 )
+        return TEST_SKIP;
+    cpuid(0x80000001, &eax, &ebx, &ecx, &edx);
+    if ( !(edx & (1u<<29)) )
+        return TEST_SKIP;
+    /* Skip this test if the CPU does not support fsgsbase. */
+    cpuid(0, &eax, &ebx, &ecx, &edx);
+    if ( eax < 7 )
+        return TEST_SKIP;
+    cpuid_count(7, 0, &eax, &ebx, &ecx, &edx);
+    if ( !(ebx & (1u<<0)) )
+        return TEST_SKIP;
+
+    /* Long mode pagetable setup: Identity map 0-16MB with 2MB mappings. */
+    *pd = (unsigned long)pd + 0x1007; /* Level 4 */
+    pd += 512;
+    *pd = (unsigned long)pd + 0x1007; /* Level 3 */
+    pd += 512;
+    for ( i = 0; i < 8; i++ )         /* Level 2 */
+        *pd++ = (i << 21) + 0x1e3;
+
+    asm volatile (
+        /* CR4.{FSGSBASE,PAE}=1 */
+        "mov $0x10020,%%ebx; "
+        "mov %%ebx,%%cr4; "
+        /* CR3 */
+        "mov %0,%%cr3; "
+        /* EFER.LME=1 */
+        "mov $0xc0000080,%%ecx; rdmsr; btsl $8,%%eax; wrmsr; "
+        /* CR0.PG=1 */
+        "mov %%cr0,%%eax; btsl $31,%%eax; mov %%eax,%%cr0; "
+        "jmp 1f; 1: "
+        /* Push LRETQ stack frame. */
+        "pushl $0; pushl $"STR(SEL_CODE32)"; pushl $0; pushl $2f; "
+        /* Jump to 64-bit mode. */
+        "ljmp $"STR(SEL_CODE64)",$1f; "
+        ".code64; 1: "
+        "movl $0x234,%%eax; "
+        ".byte 0xf3, 0x48, 0x0f, 0xae, 0xd0; " /* WRFSBASE %rax */
+        /* Jump to 32-bit mode. */
+        "movl %%esp,%%esp; "
+        "lretq; "
+        ".code32; 2:"
+        /* Read FS_BASE: should now contain 0x234 */
+        "mov $0xc0000100,%%ecx; rdmsr; mov %%eax,%%ebx; "
+        /* CR0.PG=0 */
+        "mov %%cr0,%%eax; btcl $31,%%eax; mov %%eax,%%cr0; "
+        "jmp 1f; 1:"
+        /* EFER.LME=0 */
+        "mov $0xc0000080,%%ecx; rdmsr; btcl $8,%%eax; wrmsr; "
+        /* CR4.PAE=0 */
+        "xor %%eax,%%eax; mov %%eax,%%cr4; "
+        : "=r" (dummy), "=&b" (ebx)
+        : "0" (PD_START)
+        : "eax", "ecx", "edx", "memory" );
+
+    return (ebx == 0x234) ? TEST_PASS : TEST_FAIL;
+}
+
 void perform_tests(void)
 {
     int i, passed, skipped;
@@ -204,6 +270,7 @@ void perform_tests(void)
     } tests[] = {
         { rep_io_test, "REP INSB across page boundaries" },
         { shadow_gs_test, "GS base MSRs and SWAPGS" },
+        { wrfsbase_test, "FS base MSR and WRFSBASE" },
         { NULL, NULL }
     };
 
-- 
1.7.10.4