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- Set up the kernel CS earlier in the boot process in case EFI boots the 

kernel after bypassing the decompressor and the CS descriptor used
   ends up being the EFI one which is not mapped in the identity page
   table, leading to early SEV/SNP guest communication exceptions
   resulting in the guest crashing
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Merge tag 'x86_urgent_for_v6.4_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fix from Borislav Petkov:

 - Set up the kernel CS earlier in the boot process in case EFI boots
   the kernel after bypassing the decompressor and the CS descriptor
   used ends up being the EFI one which is not mapped in the identity
   page table, leading to early SEV/SNP guest communication exceptions
   resulting in the guest crashing

* tag 'x86_urgent_for_v6.4_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/head/64: Switch to KERNEL_CS as soon as new GDT is installed
This commit is contained in:
Linus Torvalds 2023-06-11 10:14:02 -07:00
parent 65d7ca5987 a37f2699c3
commit 4c605260bc
1 changed files with 9 additions and 9 deletions
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18
arch/x86/kernel/head_64.S
View File

@ -77,6 +77,15 @@ SYM_CODE_START_NOALIGN(startup_64)
call startup_64_setup_env
popq %rsi
/* Now switch to __KERNEL_CS so IRET works reliably */
pushq $__KERNEL_CS
leaq .Lon_kernel_cs(%rip), %rax
pushq %rax
lretq
.Lon_kernel_cs:
UNWIND_HINT_END_OF_STACK
#ifdef CONFIG_AMD_MEM_ENCRYPT
/*
* Activate SEV/SME memory encryption if supported/enabled. This needs to
@ -90,15 +99,6 @@ SYM_CODE_START_NOALIGN(startup_64)
popq %rsi
#endif
/* Now switch to __KERNEL_CS so IRET works reliably */
pushq $__KERNEL_CS
leaq .Lon_kernel_cs(%rip), %rax
pushq %rax
lretq
.Lon_kernel_cs:
UNWIND_HINT_END_OF_STACK
/* Sanitize CPU configuration */
call verify_cpu