lguest: Fix guest crash when CONFIG_X86_USE_3DNOW=y

PATCH New Rusty Russell 1 participant 1 message Sep 11, 2007 3 messages not in the archive

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Rusty Russell

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2007-09-11 07:07 UTC #3 lore raw

PATCH 1/1 lguest: Fix guest crash when CONFIG_X86_USE_3DNOW=y

In reply to a message not in the archive

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 <[email protected]>

drivers/lguest/lguest.c +4 -3

diff -r 1b28730fea64 drivers/lguest/lguest.c
@@ -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