diff options
| author | Michael Ellerman <mpe@ellerman.id.au> | 2019-11-13 21:05:44 +1100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-11-28 18:29:06 +0100 |
| commit | e2c87b1ba04bd5042f6db0780ed55abaf4836378 (patch) | |
| tree | 88965b270ad14fa8f84bff3973f2f8c913f06132 /arch/powerpc/include | |
| parent | 113408cdaec11a6e34d4edabb134a335dd4896b3 (diff) | |
KVM: PPC: Book3S HV: Flush link stack on guest exit to host kernel
commit af2e8c68b9c5403f77096969c516f742f5bb29e0 upstream.
On some systems that are vulnerable to Spectre v2, it is up to
software to flush the link stack (return address stack), in order to
protect against Spectre-RSB.
When exiting from a guest we do some house keeping and then
potentially exit to C code which is several stack frames deep in the
host kernel. We will then execute a series of returns without
preceeding calls, opening up the possiblity that the guest could have
poisoned the link stack, and direct speculative execution of the host
to a gadget of some sort.
To prevent this we add a flush of the link stack on exit from a guest.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
[dja: straightforward backport to v4.14]
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/powerpc/include')
| -rw-r--r-- | arch/powerpc/include/asm/asm-prototypes.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/asm-prototypes.h b/arch/powerpc/include/asm/asm-prototypes.h index cb3da44ecbb6..c06cfdf12c0b 100644 --- a/arch/powerpc/include/asm/asm-prototypes.h +++ b/arch/powerpc/include/asm/asm-prototypes.h @@ -125,7 +125,9 @@ extern int __ucmpdi2(u64, u64); extern s32 patch__call_flush_count_cache; extern s32 patch__flush_count_cache_return; extern s32 patch__flush_link_stack_return; +extern s32 patch__call_kvm_flush_link_stack; extern long flush_count_cache; +extern long kvm_flush_link_stack; #endif /* _ASM_POWERPC_ASM_PROTOTYPES_H */ |