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[PATCH v2] hw/i386/amd_iommu: Fix maybe-uninitialized error with GCC 12
From: |
Paolo Bonzini |
Subject: |
[PATCH v2] hw/i386/amd_iommu: Fix maybe-uninitialized error with GCC 12 |
Date: |
Mon, 21 Mar 2022 15:33:46 +0100 |
Be more explicit that the loop must roll at least once. Avoids the
following warning:
FAILED: libqemu-x86_64-softmmu.fa.p/hw_i386_amd_iommu.c.o
In function 'pte_get_page_mask',
inlined from 'amdvi_page_walk' at hw/i386/amd_iommu.c:945:25,
inlined from 'amdvi_do_translate' at hw/i386/amd_iommu.c:989:5,
inlined from 'amdvi_translate' at hw/i386/amd_iommu.c:1038:5:
hw/i386/amd_iommu.c:877:38: error: 'oldlevel' may be used uninitialized
[-Werror=maybe-uninitialized]
877 | return ~((1UL << ((oldlevel * 9) + 3)) - 1);
| ~~~~~~~~~~~~~~~~^~~~
hw/i386/amd_iommu.c: In function 'amdvi_translate':
hw/i386/amd_iommu.c:906:41: note: 'oldlevel' was declared here
906 | unsigned level, present, pte_perms, oldlevel;
| ^~~~~~~~
cc1: all warnings being treated as errors
Having:
$ gcc --version
gcc (Debian 12-20220313-1) 12.0.1 20220314 (experimental)
Reported-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
hw/i386/amd_iommu.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c
index 4d13d8e697..6986ad3b87 100644
--- a/hw/i386/amd_iommu.c
+++ b/hw/i386/amd_iommu.c
@@ -913,7 +913,7 @@ static void amdvi_page_walk(AMDVIAddressSpace *as, uint64_t
*dte,
}
/* we are at the leaf page table or page table encodes a huge page */
- while (level > 0) {
+ do {
pte_perms = amdvi_get_perms(pte);
present = pte & 1;
if (!present || perms != (perms & pte_perms)) {
@@ -932,10 +932,7 @@ static void amdvi_page_walk(AMDVIAddressSpace *as,
uint64_t *dte,
}
oldlevel = level;
level = get_pte_translation_mode(pte);
- if (level == 0x7) {
- break;
- }
- }
+ } while (level > 0 && level < 7);
if (level == 0x7) {
page_mask = pte_override_page_mask(pte);
--
2.35.1
- [PATCH v2] hw/i386/amd_iommu: Fix maybe-uninitialized error with GCC 12,
Paolo Bonzini <=