From: Zachary Amsden <zach@vmware.com>
To: Andrew Morton <akpm@osdl.org>, Linus Torvalds <torvalds@osdl.org>,
Andi Kleen <ak@suse.de>,
Virtualization Mailing List <virtualization@lists.osdl.org>,
Anthony Liguori <aliguori@us.ibm.com>
Subject: [PATCH] 2.6.21 - VMI logic error
Date: Thu, 12 Apr 2007 19:28:46 -0700 [thread overview]
Message-ID: <461EEADE.8060400@vmware.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 508 bytes --]
So there is a logic error that would prevent us from ever using NOP
relocations, thus stopping any unnecessary callouts into a VMI ROM. It
doesn't affect us so much, but could conceivably affect open source
implementations of a VMI ROM in the future. It is not absolutely
critical, but it would be extremely nice to get it fixed in 2.6.21 so
there are no broken older kernels floating around that mandate having a
workaround for this or else breaking compatibility with these kernels.
Thanks,
Zach
[-- Attachment #2: vmi-logic-error.patch --]
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Fix logic error in VMI relocation processing. NOPs would always cause
a BUG_ON to fire because the != RELOCATION_NONE in the first if clause
precluding the == VMI_RELOCATION_NOP in the second clause. Make these
direct equality tests and just warn for unsupported relocation types
(which should never happen), falling back to native in that case.
Thanks to Anthony Liguori for noting this!
Signed-off-by: Zachary Amsden <zach@vmware.com>
diff -r 99800d11a3ec arch/i386/kernel/vmi.c
--- a/arch/i386/kernel/vmi.c Thu Apr 12 16:37:29 2007 -0700
+++ b/arch/i386/kernel/vmi.c Thu Apr 12 19:00:46 2007 -0700
@@ -685,11 +685,14 @@ do { \
do { \
reloc = call_vrom_long_func(vmi_rom, get_reloc, \
VMI_CALL_##vmicall); \
- if (rel->type != VMI_RELOCATION_NONE) { \
- BUG_ON(rel->type != VMI_RELOCATION_CALL_REL); \
+ if (rel->type == VMI_RELOCATION_CALL_REL) \
paravirt_ops.opname = (void *)rel->eip; \
- } else if (rel->type == VMI_RELOCATION_NOP) \
+ else if (rel->type == VMI_RELOCATION_NOP) \
paravirt_ops.opname = (void *)vmi_nop; \
+ else if (rel->type != VMI_RELOCATION_NONE) \
+ printk(KERN_WARNING "VMI: Unknown relocation " \
+ "type %d for " #vmicall"\n",\
+ rel->type); \
} while (0)
/*
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next reply other threads:[~2007-04-13 2:28 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-13 2:28 Zachary Amsden [this message]
2007-04-13 14:32 ` [PATCH] 2.6.21 - VMI logic error Andi Kleen
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