From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Subject: [RESEND,2/5] x86/MCE: Handle MCA controls in a per_cpu way From: Borislav Petkov Message-Id: <20190410172539.GF26580@zn.tnic> Date: Wed, 10 Apr 2019 19:25:39 +0200 To: "Ghannam, Yazen" Cc: "linux-edac@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "tony.luck@intel.com" , "x86@kernel.org" List-ID: T24gV2VkLCBBcHIgMTAsIDIwMTkgYXQgMDQ6NTg6MTJQTSArMDAwMCwgR2hhbm5hbSwgWWF6ZW4g d3JvdGU6Cj4gWWVzLCB1bnVzZWQgYmFua3MgaW4gdGhlIG1pZGRsZSBhcmUgY291bnRlZCBpbiB0 aGUgTUNHX0NBUFtDb3VudF0gdmFsdWUuCgpHb29kLgoKPiBPa2F5LCBzbyB5b3UncmUgc2F5aW5n IHRoZSBzeXNmcyBhY2Nlc3Mgc2hvdWxkIGZhaWwgaWYgYSBiYW5rIGlzCj4gZGlzYWJsZWQuIElz IHRoYXQgY29ycmVjdD8KCldlbGwsIHRoaW5rIGFib3V0IGl0LiBJZiBhIGJhbmsgaXMgbm90IG9w ZXJhdGlvbmFsIGZvciB3aGF0ZXZlciByZWFzb24sCndlIHNob3VsZCB0ZWxsIHRoZSB1c2VyIHRo YXQuCgo+IERvZXMgImRpc2FibGVkIiBtZWFuIG9uZSBvciBib3RoIG9mIHRoZXNlPwo+IFVudXNl ZCA9IFJBWi9XSSBpbiBoYXJkd2FyZQo+IFVuaW5pdGlhbGl6ZWQgPSBOb3QgaW5pdGlhbGl6ZWQg Ynkga2VybmVsIGR1ZSB0byBxdWlya3MsIGV0Yy4KPiAKPiBGb3IgYW4gdW51c2VkIGJhbmssIGl0 IGRvZXNuJ3QgaHVydCB0byB3cml0ZSBNQ0FfQ1RMLCBidXQgcmVhbGx5Cj4gdGhlcmUncyBubyBy ZWFzb24gdG8gZG8gc28gYW5kIGdvIHRocm91Z2ggbWNlX3Jlc3RhcnQoKS4KClllcywgYnV0IHRo YXQgYmFuayBpcyBub24tb3BlcmF0aW9uYWwgaW4gc29tZSBmb3JtLiBTbyB3ZSBzaG91bGQgcHJl dmVudAphbGwgd3JpdGVzIHRvIGl0IGJlY2F1c2UsIHdlbGwsIGl0IGlzIG5vdCBnb2luZyB0byBk byBhbnl0aGluZy4gQW5kIHRoaXMKd291bGQgYmUgYSBnb29kIHdheSB0byBnaXZlIGZlZWRiYWNr IHRvIHRoZSB1c2VyIHRoYXQgdGhhdCBpcyB0aGUgY2FzZS4KCj4gRm9yIGFuIHVuaW5pdGlhbGl6 ZWQgYmFuaywgc2hvdWxkIHdlIHByZXZlbnQgdXNlcnMgZnJvbSBvdmVycmlkaW5nIHRoZQo+IGtl cm5lbCdzIHNldHRpbmdzPwoKVGhhdCBhbGwgZGVwZW5kcyBvbiB0aGUgcXVpcmtzLiBXaGV0aGVy IHdlIHNob3VsZCBhbGxvdyB0aGVtIHRvIGJlCm92ZXJyaWRkZW4gb3Igbm90LiBJIGRvbid0IHRo aW5rIHdlJ3ZlIGV2ZXIgdGhvdWdodCBhYm91dCBpdCwgdGhvdWdoLgoKTGV0J3MgbG9vayBhdCBv bmU6CgogICAgICAgIGlmIChjLT54ODZfdmVuZG9yID09IFg4Nl9WRU5ET1JfQU1EKSB7CiAgICAg ICAgICAgICAgICBpZiAoYy0+eDg2ID09IDE1ICYmIGNmZy0+YmFua3MgPiA0KSB7CiAgICAgICAg ICAgICAgICAgICAgICAgIC8qCiAgICAgICAgICAgICAgICAgICAgICAgICAqIGRpc2FibGUgR0FS VCBUQkwgd2FsayBlcnJvciByZXBvcnRpbmcsIHdoaWNoCiAgICAgICAgICAgICAgICAgICAgICAg ICAqIHRyaXBzIG9mZiBpbmNvcnJlY3RseSB3aXRoIHRoZSBJT01NVSAmIDN3YXJlCiAgICAgICAg ICAgICAgICAgICAgICAgICAqICYgQ2VyYmVydXM6CiAgICAgICAgICAgICAgICAgICAgICAgICAq LwogICAgICAgICAgICAgICAgICAgICAgICBjbGVhcl9iaXQoMTAsICh1bnNpZ25lZCBsb25nICop Jm1jZV9iYW5rc1s0XS5jdGwpOwoKCllhaCwgc28gaWYgdGhlIHVzZXIgcmVlbmFibGVzIHRob3Nl IEdBUlQgZXJyb3JzLCB0aGVuIHNoZS9oZSB3aWxsIHNlZSBhCmxvdCBvZiBNQ0VzIHJlcG9ydGVk IGFuZCB3aWxsIG1heWJlIGNvbXBsYWluIGFib3V0IGl0LiBBbmQgdGhlbiB3ZSdsbApzYXksIGJ1 dCB3aHkgZGlkIHlvdSBlbmFibGUgdGhlbSB0aGVuLiBBbmQgc2hlL2hlJ2xsIHNheTogdWgsIGRp ZG4ndAprbm93LiBPciwgSSB3YXMganVzdCBwb2tpbmcgYXQgc3lzZnMgYW5kIHRoaXMgaGFwcGVu ZWQuCgpUaGVuIHdlIGNhbiBzYXksIHdlbGwsIGRvbid0IGRvIHRoYXQgdGhlbiEgOi0pCgpTbyBt eSBjdXJyZW50IHBvc2l0aW9uIGlzLCBtZWgsIHdobyBjYXJlcy4gQnV0IHRoZW4gSSdtIGxvb2tp bmcgYXQKYW5vdGhlciBxdWlyazoKCiAgICAgICAgaWYgKGMtPng4Nl92ZW5kb3IgPT0gWDg2X1ZF TkRPUl9JTlRFTCkgewogICAgICAgICAgICAgICAgLyoKICAgICAgICAgICAgICAgICAqIFNETSBk b2N1bWVudHMgdGhhdCBvbiBmYW1pbHkgNiBiYW5rIDAgc2hvdWxkIG5vdCBiZSB3cml0dGVuCiAg ICAgICAgICAgICAgICAgKiBiZWNhdXNlIGl0IGFsaWFzZXMgdG8gYW5vdGhlciBzcGVjaWFsIEJJ T1MgY29udHJvbGxlZAogICAgICAgICAgICAgICAgICogcmVnaXN0ZXIuCiAgICAgICAgICAgICAg ICAgKiBCdXQgaXQncyBub3QgYWxpYXNlZCBhbnltb3JlIG9uIG1vZGVsIDB4MWErCiAgICAgICAg ICAgICAgICAgKiBEb24ndCBpZ25vcmUgYmFuayAwIGNvbXBsZXRlbHkgYmVjYXVzZSB0aGVyZSBj b3VsZCBiZSBhCiAgICAgICAgICAgICAgICAgKiB2YWxpZCBldmVudCBsYXRlciwgbWVyZWx5IGRv bid0IHdyaXRlIENUTDAuCiAgICAgICAgICAgICAgICAgKi8KCiAgICAgICAgICAgICAgICBpZiAo Yy0+eDg2ID09IDYgJiYgYy0+eDg2X21vZGVsIDwgMHgxQSAmJiBjZmctPmJhbmtzID4gMCkKICAg ICAgICAgICAgICAgICAgICAgICAgbWNlX2JhbmtzWzBdLmluaXQgPSAwOwoKCndoaWNoIGJhc2lj YWxseSBwcmV2ZW50cyB0aGF0IGJhbmsgZnJvbSBiZWluZyByZWluaXRpYWxpemVkLiBTbyBJIGd1 ZXNzCndlIGhhdmUgdGhhdCBmdW5jdGlvbmFsaXR5IGFscmVhZHkgLSB3ZSBzaW1wbHkgbmVlZCB0 byBwYXkgYXR0ZW50aW9uIHRvCnctPmluaXQuCgpSaWdodD8K From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A224BC10F11 for ; 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a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1554917145; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=XcAeVmm3JHcWiuNHD4dSqbLHlPuiBy3ozgXMYTg4/oM=; b=Yx/D6BVnXY/KZiFicss72wboe1le6SCIZjYeeJZGLqzdvq0/STVREFCpbCG3SLM6SfZrIT 76N3kNkmsAB7At6D0edukNGmZ8QM4HsEIlEcDxRrpsyh2vzk9+FpR5jc+vBR4rhcA2dhQP MrQZgP6mGNWiSHZCnDKzHrjglA6cRjc= Date: Wed, 10 Apr 2019 19:25:39 +0200 From: Borislav Petkov To: "Ghannam, Yazen" Cc: "linux-edac@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "tony.luck@intel.com" , "x86@kernel.org" Subject: Re: [PATCH RESEND 2/5] x86/MCE: Handle MCA controls in a per_cpu way Message-ID: <20190410172539.GF26580@zn.tnic> References: <20190408141205.12376-1-Yazen.Ghannam@amd.com> <20190408141205.12376-3-Yazen.Ghannam@amd.com> <20190408175142.GK15689@zn.tnic> <20190409203412.GE6150@zn.tnic> <20190410164036.GC26580@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-edac-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-edac@vger.kernel.org Message-ID: <20190410172539.Kl0PCoQv-9XghXgdLwSqM5pS1ZW6XpiI-Ck5USsDNsc@z> On Wed, Apr 10, 2019 at 04:58:12PM +0000, Ghannam, Yazen wrote: > Yes, unused banks in the middle are counted in the MCG_CAP[Count] value. Good. > Okay, so you're saying the sysfs access should fail if a bank is > disabled. Is that correct? Well, think about it. If a bank is not operational for whatever reason, we should tell the user that. > Does "disabled" mean one or both of these? > Unused = RAZ/WI in hardware > Uninitialized = Not initialized by kernel due to quirks, etc. > > For an unused bank, it doesn't hurt to write MCA_CTL, but really > there's no reason to do so and go through mce_restart(). Yes, but that bank is non-operational in some form. So we should prevent all writes to it because, well, it is not going to do anything. And this would be a good way to give feedback to the user that that is the case. > For an uninitialized bank, should we prevent users from overriding the > kernel's settings? That all depends on the quirks. Whether we should allow them to be overridden or not. I don't think we've ever thought about it, though. Let's look at one: if (c->x86_vendor == X86_VENDOR_AMD) { if (c->x86 == 15 && cfg->banks > 4) { /* * disable GART TBL walk error reporting, which * trips off incorrectly with the IOMMU & 3ware * & Cerberus: */ clear_bit(10, (unsigned long *)&mce_banks[4].ctl); Yah, so if the user reenables those GART errors, then she/he will see a lot of MCEs reported and will maybe complain about it. And then we'll say, but why did you enable them then. And she/he'll say: uh, didn't know. Or, I was just poking at sysfs and this happened. Then we can say, well, don't do that then! :-) So my current position is, meh, who cares. But then I'm looking at another quirk: if (c->x86_vendor == X86_VENDOR_INTEL) { /* * SDM documents that on family 6 bank 0 should not be written * because it aliases to another special BIOS controlled * register. * But it's not aliased anymore on model 0x1a+ * Don't ignore bank 0 completely because there could be a * valid event later, merely don't write CTL0. */ if (c->x86 == 6 && c->x86_model < 0x1A && cfg->banks > 0) mce_banks[0].init = 0; which basically prevents that bank from being reinitialized. So I guess we have that functionality already - we simply need to pay attention to w->init. Right? -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.