From: Nikolay Borisov <nik.borisov@suse.com>
To: Borislav Petkov <bp@alien8.de>, X86 ML <x86@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86/srso: Disable the mitigation on unaffected configurations
Date: Mon, 14 Aug 2023 09:39:11 +0300 [thread overview]
Message-ID: <1588ed00-be11-ff9d-e4c2-12db78cca06f@suse.com> (raw)
In-Reply-To: <20230813104517.3346-1-bp@alien8.de>
On 13.08.23 г. 13:45 ч., Borislav Petkov wrote:
> From: "Borislav Petkov (AMD)" <bp@alien8.de>
>
> Skip the srso cmd line parsing which is not needed on Zen1/2 with SMT
> disabled and with the proper microcode applied (latter should be the
> case anyway) as those are not affected.
>
> Fixes: 5a15d8348881 ("x86/srso: Tie SBPB bit setting to microcode patch detection")
> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
> ---
> arch/x86/kernel/cpu/bugs.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
> index d02f73c5339d..8959a1b9fb80 100644
> --- a/arch/x86/kernel/cpu/bugs.c
> +++ b/arch/x86/kernel/cpu/bugs.c
> @@ -2418,8 +2418,10 @@ static void __init srso_select_mitigation(void)
> * IBPB microcode has been applied.
> */
> if ((boot_cpu_data.x86 < 0x19) &&
> - (!cpu_smt_possible() || (cpu_smt_control == CPU_SMT_DISABLED)))
> + (!cpu_smt_possible() || (cpu_smt_control == CPU_SMT_DISABLED))) {
> setup_force_cpu_cap(X86_FEATURE_SRSO_NO);
> + goto pred_cmd;
Actually can't you simply return, given that zen1/2 never have the SBPB
flag set? Only zen3/4 with the updated microcode?
> + }
> }
>
> if (retbleed_mitigation == RETBLEED_MITIGATION_IBPB) {
> @@ -2696,6 +2698,9 @@ static ssize_t retbleed_show_state(char *buf)
>
> static ssize_t srso_show_state(char *buf)
> {
> + if (boot_cpu_has(X86_FEATURE_SRSO_NO))
> + return sysfs_emit(buf, "Not affected\n");
> +
> return sysfs_emit(buf, "%s%s\n",
> srso_strings[srso_mitigation],
> (cpu_has_ibpb_brtype_microcode() ? "" : ", no microcode"));
next prev parent reply other threads:[~2023-08-14 6:40 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-13 10:45 [PATCH] x86/srso: Disable the mitigation on unaffected configurations Borislav Petkov
2023-08-14 6:39 ` Nikolay Borisov [this message]
2023-08-14 20:08 ` Josh Poimboeuf
2023-08-14 20:25 ` Borislav Petkov
2023-08-14 20:53 ` Josh Poimboeuf
2023-08-14 21:17 ` Borislav Petkov
2023-08-15 9:57 ` [PATCH] x86/srso: Correct the mitigation status when SMT is disabled Borislav Petkov
2023-08-15 19:58 ` Josh Poimboeuf
2023-08-15 20:17 ` Borislav Petkov
2023-08-15 21:27 ` Josh Poimboeuf
2023-08-16 8:30 ` Borislav Petkov
2023-08-16 16:07 ` Josh Poimboeuf
2023-08-16 17:35 ` Borislav Petkov
2023-08-16 18:29 ` Josh Poimboeuf
2023-08-16 18:58 ` Borislav Petkov
2023-08-17 9:07 ` Borislav Petkov
2023-08-17 14:54 ` Josh Poimboeuf
2023-08-18 10:59 ` [tip: x86/urgent] " tip-bot2 for Borislav Petkov (AMD)
2023-08-14 9:37 ` [tip: x86/urgent] x86/srso: Disable the mitigation on unaffected configurations tip-bot2 for Borislav Petkov (AMD)
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