diff options
Diffstat (limited to 'debian/patches/bugfix/x86/retbleed/0038-x86-speculation-Use-cached-host-SPEC_CTRL-value-for-.patch')
| -rw-r--r-- | debian/patches/bugfix/x86/retbleed/0038-x86-speculation-Use-cached-host-SPEC_CTRL-value-for-.patch | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/debian/patches/bugfix/x86/retbleed/0038-x86-speculation-Use-cached-host-SPEC_CTRL-value-for-.patch b/debian/patches/bugfix/x86/retbleed/0038-x86-speculation-Use-cached-host-SPEC_CTRL-value-for-.patch new file mode 100644 index 000000000..bee1127b1 --- /dev/null +++ b/debian/patches/bugfix/x86/retbleed/0038-x86-speculation-Use-cached-host-SPEC_CTRL-value-for-.patch @@ -0,0 +1,52 @@ +From: Josh Poimboeuf <jpoimboe@kernel.org> +Date: Tue, 14 Jun 2022 23:16:08 +0200 +Subject: x86/speculation: Use cached host SPEC_CTRL value for guest entry/exit +Origin: https://git.kernel.org/linus/bbb69e8bee1bd882784947095ffb2bfe0f7c9470 + +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> +--- + arch/x86/kernel/cpu/bugs.c | 12 +----------- + 1 file changed, 1 insertion(+), 11 deletions(-) + +diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c +index 9b80059c4e02..f884f9497666 100644 +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -208,7 +208,7 @@ 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 ? */ +@@ -221,15 +221,6 @@ x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest) + 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); +@@ -1397,7 +1388,6 @@ static void __init spectre_v2_select_mitigation(void) + 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); + } |