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Message-Id: <20231002220045.1014760-1-dave.hansen@linux.intel.com>
Date: Mon, 2 Oct 2023 15:00:45 -0700
From: Dave Hansen <dave.hansen@...ux.intel.com>
To: linux-kernel@...r.kernel.org, nathan@...nel.org
Cc: x86@...nel.org, acdunlap@...gle.com, ashok.raj@...el.com,
bp@...en8.de, dave.hansen@...ux.intel.com, david@...hat.com,
dionnaglaze@...gle.com, hpa@...or.com, jacobhxu@...gle.com,
jgross@...e.com, jroedel@...e.de, khalid.elmously@...onical.com,
kim.phillips@....com, kirill.shutemov@...ux.intel.com,
llvm@...ts.linux.dev, luto@...nel.org, mingo@...hat.com,
nikunj@....com, peterz@...radead.org, pgonda@...gle.com,
rientjes@...gle.com, rppt@...nel.org, seanjc@...gle.com,
tglx@...utronix.de, thomas.lendacky@....com,
Ingo Molnar <mingo@...nel.org>
Subject: [PATCH] x86/boot: Move x86_cache_alignment initialization to correct spot
c->x86_cache_alignment is initialized from c->x86_clflush_size.
However, commit fbf6449f84bf moved c->x86_clflush_size initialization
to later in boot without moving the c->x86_cache_alignment assignment.
This presumably left c->x86_cache_alignment set to zero for longer
than it should be.
The result was an oops on 32-bit kernels while accessing a pointer
at 0x20. The 0x20 came from accessing a structure member at offset
0x10 (buffer->cpumask) from a ZERO_SIZE_PTR=0x10. kmalloc() can
evidently return ZERO_SIZE_PTR when it's given 0 as its alignment
requirement.
Move the c->x86_cache_alignment initialization to be after
c->x86_clflush_size has an actual value.
Fixes: fbf6449f84bf ("x86/sev-es: Set x86_virt_bits to the correct value straight away, instead of a two-phase approach")
Cc: Adam Dunlap <acdunlap@...gle.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Jacob Xu <jacobhxu@...gle.com>
Link: https://lore.kernel.org/all/20231002200426.GA4127272@dev-arch.thelio-3990X/
---
arch/x86/kernel/cpu/common.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 8d7063e4f63c9..9c51ad5bbf319 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1141,6 +1141,7 @@ void get_cpu_address_sizes(struct cpuinfo_x86 *c)
}
}
c->x86_cache_bits = c->x86_phys_bits;
+ c->x86_cache_alignment = c->x86_clflush_size;
}
static void identify_cpu_without_cpuid(struct cpuinfo_x86 *c)
@@ -1594,8 +1595,6 @@ static void __init cpu_parse_early_param(void)
*/
static void __init early_identify_cpu(struct cpuinfo_x86 *c)
{
- c->x86_cache_alignment = c->x86_clflush_size;
-
memset(&c->x86_capability, 0, sizeof(c->x86_capability));
c->extended_cpuid_level = 0;
--
2.34.1
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