From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Ellerman Subject: Re: [PATCH RFC 3/5] powerpc/speculation: Add support for 'cpu_spec_mitigations=' cmdline options Date: Wed, 10 Apr 2019 16:06:50 +1000 Message-ID: <87pnpuwg05.fsf@concordia.ellerman.id.au> References: <91b92d8182d2f114d92c95689fcd4bb1a8dda1b0.1554396090.git.jpoimboe@redhat.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <91b92d8182d2f114d92c95689fcd4bb1a8dda1b0.1554396090.git.jpoimboe@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Josh Poimboeuf , linux-kernel@vger.kernel.org Cc: x86@kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Jiri Kosina , Waiman Long , Andrea Arcangeli , Jon Masters , Benjamin Herrenschmidt , Paul Mackerras , linuxppc-dev@lists.ozlabs.org, Martin Schwidefsky , Heiko Carstens , linux-s390@vger.kernel.org, Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org, Greg List-ID: Josh Poimboeuf writes: > Configure powerpc CPU runtime speculation bug mitigations in accordance > with the 'cpu_spec_mitigations=' cmdline options. This affects > Meltdown, Spectre v1, Spectre v2, and Speculative Store Bypass. > > The default behavior is unchanged. > > Signed-off-by: Josh Poimboeuf > --- > Documentation/admin-guide/kernel-parameters.txt | 9 +++++---- > arch/powerpc/kernel/security.c | 6 +++--- > arch/powerpc/kernel/setup_64.c | 2 +- > 3 files changed, 9 insertions(+), 8 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 29dc03971630..0e8eae1e8a25 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -2552,10 +2552,11 @@ > > off > Disable all speculative CPU mitigations. > - Equivalent to: nopti [x86] > + Equivalent to: nopti [x86, powerpc] > + nospectre_v1 [powerpc] > nospectre_v2 [x86] Not sure if you meant to omit powerpc from nospectre_v2? You have patched it in the code below. > spectre_v2_user=off [x86] > - spec_store_bypass_disable=off [x86] > + spec_store_bypass_disable=off [x86, powerpc] > l1tf=off [x86] > > auto (default) > @@ -2568,7 +2569,7 @@ > Equivalent to: pti=auto [x86] > spectre_v2=auto [x86] > spectre_v2_user=auto [x86] > - spec_store_bypass_disable=auto [x86] > + spec_store_bypass_disable=auto [x86, powerpc] > l1tf=flush [x86] > > auto,nosmt > @@ -2579,7 +2580,7 @@ > Equivalent to: pti=auto [x86] > spectre_v2=auto [x86] > spectre_v2_user=auto [x86] > - spec_store_bypass_disable=auto [x86] > + spec_store_bypass_disable=auto [x86, powerpc] > l1tf=flush,nosmt [x86] > > mminit_loglevel= > diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c > index b33bafb8fcea..5aed4ad729ba 100644 > --- a/arch/powerpc/kernel/security.c > +++ b/arch/powerpc/kernel/security.c > @@ -57,7 +57,7 @@ void setup_barrier_nospec(void) > enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) && > security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR); > > - if (!no_nospec) > + if (!no_nospec && cpu_spec_mitigations != CPU_SPEC_MITIGATIONS_OFF) > enable_barrier_nospec(enable); Adding a wrapper func that checks for CPU_SPEC_MITIGATIONS_OFF would make these a little less verbose, eg: if (!no_nospec && !cpu_spec_mitigations_off()) enable_barrier_nospec(enable); But that's a nitpick. > @@ -116,7 +116,7 @@ static int __init handle_nospectre_v2(char *p) > early_param("nospectre_v2", handle_nospectre_v2); > void setup_spectre_v2(void) > { > - if (no_spectrev2) > + if (no_spectrev2 || cpu_spec_mitigations == CPU_SPEC_MITIGATIONS_OFF) > do_btb_flush_fixups(); > else > btb_flush_enabled = true; > @@ -300,7 +300,7 @@ void setup_stf_barrier(void) > > stf_enabled_flush_types = type; > > - if (!no_stf_barrier) > + if (!no_stf_barrier && cpu_spec_mitigations != CPU_SPEC_MITIGATIONS_OFF) > stf_barrier_enable(enable); > } > > diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c > index ba404dd9ce1d..d9d796a66a79 100644 > --- a/arch/powerpc/kernel/setup_64.c > +++ b/arch/powerpc/kernel/setup_64.c > @@ -932,7 +932,7 @@ void setup_rfi_flush(enum l1d_flush_type types, bool enable) > > enabled_flush_types = types; > > - if (!no_rfi_flush) > + if (!no_rfi_flush || cpu_spec_mitigations != CPU_SPEC_MITIGATIONS_OFF) > rfi_flush_enable(enable); > } LGTM. Acked-by: Michael Ellerman (powerpc) cheers