Date:   Wed, 8 Feb 2023 15:43:48 -0800
From:   Darren Hart <darren@os.amperecomputing.com>
To:     Ard Biesheuvel <ardb@kernel.org>
Cc:     LKML <linux-kernel@vger.kernel.org>, stable@vger.kernel.org,
        linux-efi@vger.kernel.org,
        Alexandru Elisei <alexandru.elisei@gmail.com>
Subject: Re: [PATCH] arm64: efi: Force the use of SetVirtualAddressMap() on
 Altra Max machines
Message-ID: <Y+QztBs1uHnTRyyu@fedora>
References: <a968c446bde75bf019580366854349bf94e6c961.1675897882.git.darren@os.amperecomputing.com>
 <CAMj1kXF2Bi_iyjzUK2zie_pt6Vnm4QwvarHicJoRzUiX7nU0Kw@mail.gmail.com>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAMj1kXF2Bi_iyjzUK2zie_pt6Vnm4QwvarHicJoRzUiX7nU0Kw@mail.gmail.com>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?ACg+8SjvNoTUC98LnVN8p1kKpseVNgCs6w13I9QrHCLm/08zQJWoTdXEo6R+?=
 =?us-ascii?Q?MM4XAQgqyQV01Qq/EWGFtQJpcUuL3srmyWCiX2huc0FiJIuphi2Vc2Dh875c?=
 =?us-ascii?Q?04vElJ4buAOd5ldGjVPUuftIIKkdwhZ8kdmkkVaTq4Q8LfCVmWHe5/ive7KO?=
 =?us-ascii?Q?zhS+xawN7P6PmpZfEW0rApM88B01pOAaPvRylLbBZuQy1ST/R1klIMIFNMm+?=
 =?us-ascii?Q?hAFjE84ObaE6J2IoyyrqILNtLIF/j/3PXc4cYeisB3kWhA8vny/O37vxmc40?=
 =?us-ascii?Q?HPBXTCtoPBtbaSxoVMesZWeVoQIk2KM2lszbcGwc0EKak7+Sgug8kpExWGdx?=
 =?us-ascii?Q?EtNR5PQdGSZDpsWlk0PxT9vXdEpgxRlULB54LlYNeGKxEikHp4tnVrUvsjbU?=
 =?us-ascii?Q?tqrw47eRcmvCx40oe/Upjp6NLc4FlWziR9Txxx2GrlTmJ3QsIHbwtii+XDfu?=
 =?us-ascii?Q?vzykwv4aQHJt5XzYmR5If2B+btkOm3j3oCF+BRPNfRWrtPblx0G44kBnIBxm?=
 =?us-ascii?Q?ZSdLhy9HWO+C5wlezjaa/hP6ZvebLgVntAQE3ZpoLNqxkQNeCPRgRED3OyXq?=
 =?us-ascii?Q?ONDXe5hGR32D3FC6uprbyHpr4JdKeeSyxbWYNK9fJwxgY0MGDcDTd5LfpHCX?=
 =?us-ascii?Q?JUdQq0k+ij99J+PUSOHjTUWBWyfKSDb2condJ3ottDAhPFJ09BgRIBJb/oBL?=
 =?us-ascii?Q?+GgzO8HpkqTLF8h6TOmBaUKPwLW3zMu1b+Tz2bIl5NtV/Hp3BewuUuyK/oV0?=
 =?us-ascii?Q?A0Ahl3GvRGgZvnf8TXn4MSAp8D4gXURC+2552VSwjHAdBp1l5UHGCGs91Fwx?=
 =?us-ascii?Q?ZZuFy7bgDVHYsnXOOF/NlidmUBBJBUF1kfUIQaoFC5EyDmowUK62CsJ6zlsS?=
 =?us-ascii?Q?J0KKrIEOSgHglS9kMZ+4rHzMJpf5kkgZpEaCKoFqe/7MV21qphkhgma8hQtd?=
 =?us-ascii?Q?qwU4NWcF+MHpQGEuXWNC2jPEjiR5UNks0AH9keVXo2y/V5Q5wM1/TVHZD1Nx?=
 =?us-ascii?Q?4rqUuk77RNpsk1DEsiPSM5q0LUbnikjEcLpv7EUvLyx/a9r2UAx//DxhADDm?=
 =?us-ascii?Q?erTRhuPRRl5MrFcKz7ay1LHWWnFnJ8Woeun4udEQGa1COs486GfmanJxlqGP?=
 =?us-ascii?Q?KA6nJJqCGXpfbuzTPY3wTShjMPjTLpfoYYbwc6xFszwXnjD3JoW61ls16bVM?=
 =?us-ascii?Q?hgUyhdL/4o6oYuZte7JUcM4euQ5vpXF7a1CELKWbLwvsgEI68kApUqCRBM0k?=
 =?us-ascii?Q?/2dta2UYWc7d1618peLGPP6+URI19NuQxG/Ln/11Dpj6BiRrs6kJUlmEowF8?=
 =?us-ascii?Q?IsfuGddIqdWoZ9a/V80RCJMgkySgsE/k6W+2of1P5hUFIe+HYoqg/SsZ/tA7?=
 =?us-ascii?Q?vgv6m1mOQyC1nbrTTg/e9tRyx8yPI/PTO1A754DidMMB6kuvUnV0T8tvwfjL?=
 =?us-ascii?Q?tJZ05h9mD85KVbDikrp+irf9uLq68o2pV3RjPfBAMkxuQbgF+1oumy3Dqdtl?=
 =?us-ascii?Q?d2eHtllmZg+R6w1h9WvFUP5EV2cYZVotp7OR3b2pzTk6NNZu1YRbRBV2FAQR?=
 =?us-ascii?Q?VZOvZLau1SPRbXf0U4uRKStWEvHEBzsnnzfGhx7yLO8BRASgUPTALYISt7V3?=
 =?us-ascii?Q?P+Q0zK0O6qc9sWwmHsK0pT0=3D?=
X-OriginatorOrg: os.amperecomputing.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 4c85db96-2e58-4fbc-b8f2-08db0a2e5435
X-MS-Exchange-CrossTenant-AuthSource: SJ0PR01MB7432.prod.exchangelabs.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Feb 2023 23:43:50.2219
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 3bc2b170-fd94-476d-b0ce-4229bdc904a7
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: /Qz0ODgKRTWviQBkKmwMTPl/cxsQTnszX0BSoZHyCzZAe6yzWG71n5x2yX/neJ9p4nCSB21lEJ6ONHJCiBzlp/iYNZhusEtpkFDfJBqA6JIJOEOSNPWulACfCFpZCXjC
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN6PR01MB3249
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Feb 09, 2023 at 12:16:46AM +0100, Ard Biesheuvel wrote:
> Hello Darren,
> 
> On Thu, 9 Feb 2023 at 00:14, Darren Hart <darren@os.amperecomputing.com> wrote:
> >
> > Commit 550b33cfd445 ("arm64: efi: Force the use of SetVirtualAddressMap()
> > on Altra machines") identifies the Altra family via the family field in
> > the type#1 SMBIOS record. Altra Max machines are similarly affected but
> > not detected with the strict strcmp test.
> >
> > Rather than risk greedy matching with strncmp, add a second test for
> > Altra Max. Do not refactor to handle multiple tests as these should be
> > the only two needed.
> >
> 
> Famous last words ...

Indeed, I nearly included that myself...

> 
> Unfortunately, I just had a report the other day that 'eMAG' and
> 'Server' (!) are also being used.
> 
> https://lore.kernel.org/all/20230131040355.3116-1-justin.he@arm.com/
> 

OK, so in order to workaround this in the kernel, we need a better way to match.
Unfortunately, this is specific to the oem platform, and the oem controls those
strings.

Thanks for the pointer, will go mull this over and see if I can come up with
something better.

In the meantime, would you consider matching on:
Altra
Altra Max
eMAG

to capture the bulk of the systems until we have a better solution?

Thanks,

Darren

> 
> > Fixes: 550b33cfd445 ("arm64: efi: Force the use of SetVirtualAddressMap() on Altra machines")
> > Cc: <stable@vger.kernel.org> # 6.1.x
> > Cc: <linux-efi@vger.kernel.org>
> > Cc: Alexandru Elisei <alexandru.elisei@gmail.com>
> > Cc: Ard Biesheuvel <ardb@kernel.org>
> > Signed-off-by: Darren Hart <darren@os.amperecomputing.com>
> > ---
> >  drivers/firmware/efi/libstub/arm64.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/firmware/efi/libstub/arm64.c b/drivers/firmware/efi/libstub/arm64.c
> > index ff2d18c42ee7..97f4423059c7 100644
> > --- a/drivers/firmware/efi/libstub/arm64.c
> > +++ b/drivers/firmware/efi/libstub/arm64.c
> > @@ -19,10 +19,10 @@ static bool system_needs_vamap(void)
> >         const u8 *type1_family = efi_get_smbios_string(1, family);
> >
> >         /*
> > -        * Ampere Altra machines crash in SetTime() if SetVirtualAddressMap()
> > -        * has not been called prior.
> > +        * Ampere Altra and Altra Max machines crash in SetTime() if
> > +        * SetVirtualAddressMap() has not been called prior.
> >          */
> > -       if (!type1_family || strcmp(type1_family, "Altra"))
> > +       if (!type1_family || (strcmp(type1_family, "Altra") && strcmp(type1_family, "Altra Max")))
> >                 return false;
> >
> >         efi_warn("Working around broken SetVirtualAddressMap()\n");
> > --
> > 2.34.3
> >

-- 
Darren Hart
Ampere Computing / OS and Kernel