[PATCH v6 2/3] x86: Read MSR_ARCH_CAPS immediately after early_microcode_init()

[Alejandro Vallejo <alejandro.vallejo@xxxxxxxxx>]

Move MSR_ARCH_CAPS read code from tsx_init() to early_cpu_init(). Because
microcode updates might make them that MSR to appear/have different values
we also must reload it after a microcode update in early_microcode_init().

Signed-off-by: Alejandro Vallejo <alejandro.vallejo@xxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v6:
 * Invert logic of a verbosity-guard to reduce diff (Jan)
 * Reflow last printk in v5/patch3:early_cpu_init() for line length (Jan)
 * Rewrite comment for the early_cpu_init(false) statement (Jan)
---
 xen/arch/x86/cpu/common.c         | 20 +++++++++++++++-----
 xen/arch/x86/cpu/microcode/core.c |  9 +++++++++
 xen/arch/x86/include/asm/setup.h  |  2 +-
 xen/arch/x86/setup.c              |  2 +-
 xen/arch/x86/tsx.c                | 16 ++++------------
 5 files changed, 30 insertions(+), 19 deletions(-)

diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index cfcdaace12..2b9cc680ac 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -303,7 +303,7 @@ static inline u32 phys_pkg_id(u32 cpuid_apic, int index_msb)
 
    WARNING: this function is only called on the BP.  Don't add code here
    that is supposed to run on all CPUs. */
-void __init early_cpu_init(void)
+void __init early_cpu_init(bool verbose)
 {
        struct cpuinfo_x86 *c = &boot_cpu_data;
        u32 eax, ebx, ecx, edx;
@@ -324,6 +324,8 @@ void __init early_cpu_init(void)
        case X86_VENDOR_SHANGHAI: this_cpu = &shanghai_cpu_dev; break;
        case X86_VENDOR_HYGON:    this_cpu = &hygon_cpu_dev;    break;
        default:
+               if (!verbose)
+                       break;
                printk(XENLOG_ERR
                       "Unrecognised or unsupported CPU vendor '%.12s'\n",
                       c->x86_vendor_id);
@@ -340,10 +342,13 @@ void __init early_cpu_init(void)
        c->x86_capability[FEATURESET_1d] = edx;
        c->x86_capability[FEATURESET_1c] = ecx;
 
-       printk(XENLOG_INFO
-              "CPU Vendor: %s, Family %u (%#x), Model %u (%#x), Stepping %u 
(raw %08x)\n",
-              x86_cpuid_vendor_to_str(c->x86_vendor), c->x86, c->x86,
-              c->x86_model, c->x86_model, c->x86_mask, eax);
+       if (verbose)
+               printk(XENLOG_INFO
+                      "CPU Vendor: %s, Family %u (%#x), "
+                      "Model %u (%#x), Stepping %u (raw %08x)\n",
+                      x86_cpuid_vendor_to_str(c->x86_vendor), c->x86,
+                      c->x86, c->x86_model, c->x86_model, c->x86_mask,
+                      eax);
 
        if (c->cpuid_level >= 7) {
                uint32_t max_subleaf;
@@ -352,6 +357,11 @@ void __init early_cpu_init(void)
                            &c->x86_capability[FEATURESET_7c0],
                            &c->x86_capability[FEATURESET_7d0]);
 
+               if (test_bit(X86_FEATURE_ARCH_CAPS, c->x86_capability))
+                       rdmsr(MSR_ARCH_CAPABILITIES,
+                             c->x86_capability[FEATURESET_m10Al],
+                             c->x86_capability[FEATURESET_m10Ah]);
+
                if (max_subleaf >= 1)
                        cpuid_count(7, 1, &eax, &ebx, &ecx,
                                    &c->x86_capability[FEATURESET_7d1]);
diff --git a/xen/arch/x86/cpu/microcode/core.c 
b/xen/arch/x86/cpu/microcode/core.c
index 71e3944cf2..44bc0fafa3 100644
--- a/xen/arch/x86/cpu/microcode/core.c
+++ b/xen/arch/x86/cpu/microcode/core.c
@@ -887,5 +887,14 @@ int __init early_microcode_init(unsigned long *module_map,
     if ( ucode_mod.mod_end || ucode_blob.size )
         rc = early_microcode_update_cpu();
 
+    /*
+     * Some CPUID leaves and MSRs are only present after microcode updates
+     * on some processors. We take the chance here to make sure what little
+     * state we have already probed is re-probed in order to ensure we do
+     * not use stale values. tsx_init() in particular needs to have up to
+     * date MSR_ARCH_CAPS.
+     */
+    early_cpu_init(false);
+
     return rc;
 }
diff --git a/xen/arch/x86/include/asm/setup.h b/xen/arch/x86/include/asm/setup.h
index ae0dd3915a..df59a4cd28 100644
--- a/xen/arch/x86/include/asm/setup.h
+++ b/xen/arch/x86/include/asm/setup.h
@@ -15,7 +15,7 @@ extern uint64_t boot_tsc_stamp;
 
 extern void *stack_start;
 
-void early_cpu_init(void);
+void early_cpu_init(bool verbose);
 void early_time_init(void);
 
 void set_nr_cpu_ids(unsigned int max_cpus);
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 74e3915a4d..bdf66e80ac 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1211,7 +1211,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
         panic("Bootloader provided no memory information\n");
 
     /* This must come before e820 code because it sets paddr_bits. */
-    early_cpu_init();
+    early_cpu_init(true);
 
     /* Choose shadow stack early, to set infrastructure up appropriately. */
     if ( !boot_cpu_has(X86_FEATURE_CET_SS) )
diff --git a/xen/arch/x86/tsx.c b/xen/arch/x86/tsx.c
index 80c6f4cedd..50d8059f23 100644
--- a/xen/arch/x86/tsx.c
+++ b/xen/arch/x86/tsx.c
@@ -39,9 +39,10 @@ void tsx_init(void)
     static bool __read_mostly once;
 
     /*
-     * This function is first called between microcode being loaded, and CPUID
-     * being scanned generally.  Read into boot_cpu_data.x86_capability[] for
-     * the cpu_has_* bits we care about using here.
+     * This function is first called between microcode being loaded, and
+     * CPUID being scanned generally. early_cpu_init() has already prepared
+     * the feature bits needed here. And early_microcode_init() has ensured
+     * they are not stale after the microcode update.
      */
     if ( unlikely(!once) )
     {
@@ -49,15 +50,6 @@ void tsx_init(void)
 
         once = true;
 
-        if ( boot_cpu_data.cpuid_level >= 7 )
-            boot_cpu_data.x86_capability[FEATURESET_7d0]
-                = cpuid_count_edx(7, 0);
-
-        if ( cpu_has_arch_caps )
-            rdmsr(MSR_ARCH_CAPABILITIES,
-                  boot_cpu_data.x86_capability[FEATURESET_m10Al],
-                  boot_cpu_data.x86_capability[FEATURESET_m10Ah]);
-
         has_rtm_always_abort = cpu_has_rtm_always_abort;
 
         if ( cpu_has_tsx_ctrl && cpu_has_srbds_ctrl )
-- 
2.34.1