[PATCH v2] i386: flush cache only on VIA C3 and earlier

* [PATCH v2] i386: flush cache only on VIA C3 and earlier
@ 2023-07-06 21:33 ValdikSS
  2023-10-05 16:57 ` Daniel Kiper
  0 siblings, 1 reply; 3+ messages in thread
From: ValdikSS @ 2023-07-06 21:33 UTC (permalink / raw)
  To: grub-devel

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

See: https://savannah.gnu.org/bugs/?45149
See: commit 25492a0f047cb7a6583ae195568599c296a604d6
---
 grub-core/kern/i386/pc/init.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/grub-core/kern/i386/pc/init.c b/grub-core/kern/i386/pc/init.c
index 27bc68b8a..7f08d2067 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, procinfo;
   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, procinfo, /* Don't care */ manufacturer[0],
+                  manufacturer[2], manufacturer[1]);
+      /* Check model, apply only to VIA C3 and lower */
+      if (((procinfo & 0xF0) >> 4 | (procinfo & 0xF0000) >> 12) > 10)
+        return;
+    }
+
   grub_bios_via_workaround1 = 0x090f;
   grub_bios_via_workaround2 = 0x090f;
   asm volatile ("wbinvd");
-- 
2.41.0



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