From: Josh Poimboeuf jpoimboe@kernel.org
commit bbb69e8bee1bd882784947095ffb2bfe0f7c9470 upstream.
There's no need to recalculate the host value for every entry/exit. Just use the cached value in spec_ctrl_current().
Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Signed-off-by: Borislav Petkov bp@suse.de Signed-off-by: Thadeu Lima de Souza Cascardo cascardo@canonical.com Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/cpu/bugs.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-)
--- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -199,7 +199,7 @@ void __init check_bugs(void) void x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest) { - u64 msrval, guestval, hostval = x86_spec_ctrl_base; + u64 msrval, guestval, hostval = spec_ctrl_current(); struct thread_info *ti = current_thread_info();
/* Is MSR_SPEC_CTRL implemented ? */ @@ -212,15 +212,6 @@ x86_virt_spec_ctrl(u64 guest_spec_ctrl, guestval = hostval & ~x86_spec_ctrl_mask; guestval |= guest_spec_ctrl & x86_spec_ctrl_mask;
- /* SSBD controlled in MSR_SPEC_CTRL */ - if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) || - static_cpu_has(X86_FEATURE_AMD_SSBD)) - hostval |= ssbd_tif_to_spec_ctrl(ti->flags); - - /* Conditional STIBP enabled? */ - if (static_branch_unlikely(&switch_to_cond_stibp)) - hostval |= stibp_tif_to_spec_ctrl(ti->flags); - if (hostval != guestval) { msrval = setguest ? guestval : hostval; wrmsrl(MSR_IA32_SPEC_CTRL, msrval); @@ -1353,7 +1344,6 @@ static void __init spectre_v2_select_mit pr_err(SPECTRE_V2_EIBRS_EBPF_MSG);
if (spectre_v2_in_ibrs_mode(mode)) { - /* Force it so VMEXIT will restore correctly */ x86_spec_ctrl_base |= SPEC_CTRL_IBRS; write_spec_ctrl_current(x86_spec_ctrl_base, true); }