From: ValdikSS <iam@valdikss.org.ru>
Date: Fri, 6 Oct 2023 17:13:51 +0000 (+0300)
Subject: kern/i386/pc/init: Flush cache only on VIA C3 and earlier
X-Git-Tag: grub-2.12~55
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cab04dcda34a9419c7367279c2f309d4becde184;p=thirdparty%2Fgrub.git

kern/i386/pc/init: Flush cache only on VIA C3 and earlier

The code flushes the cache on VIA processors unconditionally which
is excessive. Check for cpuid family and execute wbinvd only on C3
and earlier.

Fixes: https://savannah.gnu.org/bugs/?45149
Fixes: 25492a0f0 (Add wbinvd around bios call.)

Signed-off-by: ValdikSS <iam@valdikss.org.ru>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---

diff --git a/grub-core/kern/i386/pc/init.c b/grub-core/kern/i386/pc/init.c
index 27bc68b8a..326d491c5 100644
--- a/grub-core/kern/i386/pc/init.c
+++ b/grub-core/kern/i386/pc/init.c
@@ -191,7 +191,7 @@ extern grub_uint16_t grub_bios_via_workaround1, grub_bios_via_workaround2;
 static void
 grub_via_workaround_init (void)
 {
-  grub_uint32_t manufacturer[3], max_cpuid;
+  grub_uint32_t manufacturer[3], max_cpuid, proc_info;
   if (! grub_cpu_is_cpuid_supported ())
     return;
 
@@ -200,6 +200,15 @@ grub_via_workaround_init (void)
   if (grub_memcmp (manufacturer, "CentaurHauls", 12) != 0)
     return;
 
+  if (max_cpuid > 0)
+    {
+      grub_cpuid (1, proc_info, /* Don't care. */ manufacturer[0],
+                  manufacturer[2], manufacturer[1]);
+      /* Check model, apply only to VIA C3 and lower. */
+      if (((proc_info & 0xf0) >> 4 | (proc_info & 0xf0000) >> 12) > 10)
+        return;
+    }
+
   grub_bios_via_workaround1 = 0x090f;
   grub_bios_via_workaround2 = 0x090f;
   asm volatile ("wbinvd");