From f58b63857ae38b4484185b799a2759274b930c92 Mon Sep 17 00:00:00 2001 From: Brian Gerst Date: Thu, 23 Jan 2025 14:07:36 -0500 Subject: [PATCH] x86/pvh: Use fixed_percpu_data for early boot GSBASE Instead of having a private area for the stack canary, use fixed_percpu_data for GSBASE like the native kernel. Signed-off-by: Brian Gerst Signed-off-by: Ingo Molnar Reviewed-by: Ard Biesheuvel Cc: Linus Torvalds Link: https://lore.kernel.org/r/20250123190747.745588-5-brgerst@gmail.com --- arch/x86/platform/pvh/head.S | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/arch/x86/platform/pvh/head.S b/arch/x86/platform/pvh/head.S index 4733a5f467b81..723f181b222ab 100644 --- a/arch/x86/platform/pvh/head.S +++ b/arch/x86/platform/pvh/head.S @@ -173,10 +173,15 @@ SYM_CODE_START(pvh_start_xen) 1: UNWIND_HINT_END_OF_STACK - /* Set base address in stack canary descriptor. */ - mov $MSR_GS_BASE,%ecx - leal canary(%rip), %eax - xor %edx, %edx + /* + * Set up GSBASE. + * Note that on SMP the boot CPU uses the init data section until + * the per-CPU areas are set up. + */ + movl $MSR_GS_BASE,%ecx + leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx + movq %edx, %eax + shrq $32, %rdx wrmsr /* Call xen_prepare_pvh() via the kernel virtual mapping */ @@ -238,8 +243,6 @@ SYM_DATA_START_LOCAL(gdt_start) SYM_DATA_END_LABEL(gdt_start, SYM_L_LOCAL, gdt_end) .balign 16 -SYM_DATA_LOCAL(canary, .fill 48, 1, 0) - SYM_DATA_START_LOCAL(early_stack) .fill BOOT_STACK_SIZE, 1, 0 SYM_DATA_END_LABEL(early_stack, SYM_L_LOCAL, early_stack_end)