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Peter Anvin" , linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/3] x86/bugs: Simplify SSB cmdline parsing Message-ID: <20250818174157.c6bzy5bgw54fopgi@desk> References: <20250811142659.152248-1-david.kaplan@amd.com> <20250811142659.152248-4-david.kaplan@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250811142659.152248-4-david.kaplan@amd.com> On Mon, Aug 11, 2025 at 09:26:59AM -0500, David Kaplan wrote: > Simplify the SSB command line parsing by selecting a mitigation directly, > as is done in most of the simpler vulnerabilities. Use early_param instead > of cmdline_find_option for consistency with the other mitigation > selections. > > Signed-off-by: David Kaplan > --- > arch/x86/kernel/cpu/bugs.c | 118 ++++++++++++------------------------- > 1 file changed, 39 insertions(+), 79 deletions(-) > > diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c > index 19a3891953c3..3766dff9a699 100644 > --- a/arch/x86/kernel/cpu/bugs.c > +++ b/arch/x86/kernel/cpu/bugs.c > @@ -2625,16 +2625,8 @@ void cpu_bugs_smt_update(void) > #undef pr_fmt > #define pr_fmt(fmt) "Speculative Store Bypass: " fmt > > -static enum ssb_mitigation ssb_mode __ro_after_init = SPEC_STORE_BYPASS_NONE; > - > -/* The kernel command line selection */ > -enum ssb_mitigation_cmd { > - SPEC_STORE_BYPASS_CMD_NONE, > - SPEC_STORE_BYPASS_CMD_AUTO, > - SPEC_STORE_BYPASS_CMD_ON, > - SPEC_STORE_BYPASS_CMD_PRCTL, > - SPEC_STORE_BYPASS_CMD_SECCOMP, > -}; > +static enum ssb_mitigation ssb_mode __ro_after_init = > + IS_ENABLED(CONFIG_MITIGATION_SSB) ? SPEC_STORE_BYPASS_PRCTL : SPEC_STORE_BYPASS_NONE; Other mitigations default to "AUTO", but not this one. Isn't that something that attack-vector controls rely on?