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Subject[PATCH] lguest: Fix guest crash when CONFIG_X86_USE_3DNOW=y
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One of the very first things lguest_init() does is a memcpy.  On
Athlon/Duron/K7 or CyrixIII/VIA-C3 or Geode GX/LX, this tries to use
MMX.

memcpy -> _mmx_memcpy -> kernel_fpu_begin -> clts -> paravirt_ops.clts

But we haven't set paravirt_ops.clts yet, so we do the native version
and crash. The simplest solution is to use __memcpy.

Thanks to Michael Rasenberger for the bug report.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff -r 1b28730fea64 drivers/lguest/lguest.c
--- a/drivers/lguest/lguest.c Tue Sep 11 13:53:31 2007 +1000
+++ b/drivers/lguest/lguest.c Tue Sep 11 16:28:49 2007 +1000
@@ -964,11 +964,12 @@ __init void lguest_init(void *boot)
{
/* Copy boot parameters first: the Launcher put the physical location
* in %esi, and head.S converted that to a virtual address and handed
- * it to us. */
- memcpy(&boot_params, boot, PARAM_SIZE);
+ * it to us. We use "__memcpy" because "memcpy" sometimes tries to do
+ * tricky things to go faster, and we're not ready for that. */
+ __memcpy(&boot_params, boot, PARAM_SIZE);
/* The boot parameters also tell us where the command-line is: save
* that, too. */
- memcpy(boot_command_line, __va(boot_params.hdr.cmd_line_ptr),
+ __memcpy(boot_command_line, __va(boot_params.hdr.cmd_line_ptr),
COMMAND_LINE_SIZE);

/* We're under lguest, paravirt is enabled, and we're running at

-
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