From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 296184430 for ; Wed, 26 Mar 2025 21:29:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743024572; cv=none; b=muae3vpkXs7I2rkhC6WMZVwOTgkAXnb5+t9GGVZ12lMXCvrctuBL+oV8H2/r2KDRUDv2uK4ulRb32C/oHeT/3eaXhJ9imx2HcRuWu2cAtanrU4QER2O8HAwImyQfQxfhL31T9/hbEAZknxEJuWHRwPsfuqGFofOpqcbwXFj1elo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743024572; c=relaxed/simple; bh=U/QNVHD9GlOlEUG/VEeH8nSY88NV88yWPEcw1EmM+oA=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=JQVJmAN6g0cqfJYy3z6OTkivFYRdvPE3m9dP2uAjrsHthmYjnzz2UlYoKENHVC9jkV36hvVhqvlHLTf77dQVSUFDgwWPC9wKB9g33mhkQbeTcd+9PPnOnV59pEPcYHhe1qZrio1IgTZlb8dwyuPz7Th5xfqGB0EmwJ1YIW/dNAo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--colinmitchell.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=y0tBBETj; arc=none smtp.client-ip=209.85.214.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--colinmitchell.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="y0tBBETj" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-2254e500a73so4356295ad.0 for ; Wed, 26 Mar 2025 14:29:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1743024570; x=1743629370; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=4ePkkCPe4N3YuNMZ8IiEAqlfQIXgkmbf4lUcWGQ8Jt4=; b=y0tBBETj3d3Thh3EOpMYmJ4uimEeCT8wwPsEtW3ECGT//KldJCNS+wtqjQF/Ep6UuY wa8O5SOtMq16N6N9QqSSO2PhGnZDAZvuMnyL3nslMUvT4dd1yCv0+Z58ahsEgVV7q1my qrvknF1yFTKgjV3d9vfOLT5L7PxqO7bXxM7PRpaiUzbIHzSVKq/BI6+BtiFLSXGoDYnp vd35kJfoEnr3vVJu/kGF+4h6wJ41/Gg84yyZeIPdj48luq3b2CV9sVpInHCghbpsthiC YT/XA0jIaIvn2cFXcOiwdQ/z/OYlUNsj0eA5D//wak0Uznl+cfcVzXSuizhhTw4IaK+l ITuw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1743024570; x=1743629370; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=4ePkkCPe4N3YuNMZ8IiEAqlfQIXgkmbf4lUcWGQ8Jt4=; b=MXeRI+Yo4TBBizdm46FKRvtPqVchun8GICLn7CYwBO/ipvl71zDM43Hf1w+lmYO6XX f0+BkjU2+xD8RywI1achykw/hzsZd8/1YTr7LDBXK151Asrw57OWWvshEk5kq1dWOwOm ARTKwlv+qzOsFqrXoRxFGy58qqVBXNcn6VfA2zKjexvc2cjJB8xDWM1GmZOXSn0hfnHx gTg4stzdWmum7kOJjR3dM4piz0ru6WMkTXNxexFX/skf/UQleINnesbk8A1Sz9mPW2Fj R5DnrkNXp4IZW36tZPJIajFp4LKSoJBYPeN9nytVTtBTW5gF6kmc8xFyTLcRSgBxidE0 qOeg== X-Forwarded-Encrypted: i=1; AJvYcCWbAGJ4vjktgHENVHItox7fjv4dzJqxyvo7sdMr7y6JoEf9fchj/BvZsX1PhggkWkjkhJcQmVGzovcbFfk=@vger.kernel.org X-Gm-Message-State: AOJu0YwESLR1dOecQLp7n80Qpo18MZlGNG1djDDnjW4xu3kjHer/lLDp +lrdw0BxyvsbAY2MKRgAVVf0s2Iro/yOOzLiYNMgc0ykYakLBBWZsiCmT5gCHZyvkl1XzAQjyqX qKqKAqY3rMYqcFp1TXkVmLduXSF36CA== X-Google-Smtp-Source: AGHT+IECHrGH2YtJBZxqnBaK0vvOGtBKjm36ZJE+wsbQNbDv3xVBnCGsaqDsSmtRCMheHW1Yz5R+mY6VPSt//Quts2Qu X-Received: from pfbb8.prod.google.com ([2002:a05:6a00:ac88:b0:739:3659:ad9]) (user=colinmitchell job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:2290:b0:736:3c6a:be02 with SMTP id d2e1a72fcca58-739610373e4mr1354749b3a.11.1743024570397; Wed, 26 Mar 2025 14:29:30 -0700 (PDT) Date: Wed, 26 Mar 2025 14:29:28 -0700 In-Reply-To: <526df712-6091-4b04-97d5-9007789dc750@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <526df712-6091-4b04-97d5-9007789dc750@intel.com> X-Mailer: git-send-email 2.49.0.472.ge94155a9ec-goog Message-ID: <20250326212928.2360063-1-colinmitchell@google.com> Subject: Re: [PATCH 0/6] x86/microcode: Support for Intel Staging Feature From: Colin Mitchell To: dave.hansen@intel.com Cc: bp@alien8.de, chang.seok.bae@intel.com, colinmitchell@google.com, dave.hansen@linux.intel.com, linux-kernel@vger.kernel.org, mingo@redhat.com, tglx@linutronix.de, x86@kernel.org Content-Type: text/plain; charset="UTF-8" > On 2/28/25 14:52, Borislav Petkov wrote: > You can't load any microcode anymore if you've disabled the legacy method > too. Staging, if I've read the code correctly here, is only used for late loading. There is performance reason to use staging for early kernel microcode loading pre-SMP. Therefore, if staging perpetually fails, it can be applied without staging on the next reboot. > On 2/28/25 15:23, Dave Hansen wrote: > You seem to be saying that you'd rather be (for instance) insecure > running old microcode than have the latency blip from a legacy microcode > load. > What action would you take if a staging-load fails? Retry again a few > times? Go back to the CPU vendor and get a new image? Or just ignore it? That's correct, but the latency tradeoff scales with the platform specific size of the microcode patch. I'd prefer to have a more deterministic update path and believe the potential latency blip would be significant enough to justify the option. Adding configuration would allow me to handle the error as needed. A retry loop would be a first step but I could also look to migrate VMs off the machine if the platform specific latency blip would negatively affect sensitive guest VMs. While an ideal solution imo would then allow me to force legacy loading, I could also settle with it being done through a reboot where early boot would already skip staging.