The following commit has been merged into the x86/mm branch of tip:
Commit-ID: 3e32552652917f10c0aa8ac75cdc8f0b8d257dec
Gitweb: https://git.kernel.org/tip/3e32552652917f10c0aa8ac75cdc8f0b8d257dec
Author: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
AuthorDate: Mon, 02 Oct 2023 15:00:45 -07:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Tue, 03 Oct 2023 09:27:12 +02:00
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:
fbf6449f84bf ("x86/sev-es: Set x86_virt_bits to the correct value straight away, instead of a two-phase approach")
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")
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20231002220045.1014760-1-dave.hansen@xxxxxxxxxxxxxxx
---
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 8d7063e..9c51ad5 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;
|