From: Dave Hansen Date: Mon, 2 Oct 2023 22:00:45 +0000 (-0700) Subject: x86/boot: Move x86_cache_alignment initialization to correct spot X-Git-Tag: io_uring-6.7-2023-11-10~102^2~7 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=3e32552652917f10c0aa8ac75cdc8f0b8d257dec;p=linux-block.git 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 Signed-off-by: Ingo Molnar Tested-by: Nathan Chancellor Link: https://lore.kernel.org/r/20231002220045.1014760-1-dave.hansen@linux.intel.com --- diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 8d7063e4f63c..9c51ad5bbf31 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;