From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9B6A67404E for ; Mon, 17 Feb 2025 20:32:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.184 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739824353; cv=none; b=EPtby8S73QkjPxSMVq8KEuukxwGmvgVQJ3icJvYuWa3BinzFVgOZrlMHX4tweLUvKwjMq2QqRx5HDA5OaypSerPnvGEw09ytka3YArNH2Xw8DwAxWQBaNTdOJVHAAocVkwfk8HHl0Udk3GahOFV4a7hUyjfgTCg3UjdGiq3xawA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739824353; c=relaxed/simple; bh=2htEmpCLitWuFojd6Br41Qj7YGgsq7kvZml7PH9wjKY=; h=MIME-Version:Date:Content-Type:From:Message-ID:Subject:To:Cc: In-Reply-To:References; b=IIc+b2ZFAPYv+aPIeFh35+CSZmOpJaJWNy87VQ4qACBkA4kK2RqX6/V2tIC0qgtZS6l/4q9mFFmSFrvC2ifUR8PPhCBxGhg1UzRDtPlKsKPrznBR7DvQx8wA0AJ6DXF/ZE4L5o9ZIMrFIvBipWcHeOYh5shr9aXmfQdMx05txFA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=oXFl8d9z; arc=none smtp.client-ip=91.218.175.184 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="oXFl8d9z" Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1739824348; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JYtoD69KFLVbOsuGYYgyc74+hUVe2DJa6zqPj49fVaI=; b=oXFl8d9z5cAqbfIkMZhRuQ0L7zOM37IT2RF14JQ1piNIUcx4SYRlWeYVCrswoVlEvNszGg qfpQv+eEfKRfH63qeO6qzfgJ34LMCQAs+6Maqd3A/+F0MlM8uQ6qy9E4CY8a+WQ6EPWuXB 43K1di0mG4TzLQy7/S3gsthicC1PpuU= Date: Mon, 17 Feb 2025 20:32:26 +0000 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: "Yosry Ahmed" Message-ID: TLS-Required: No Subject: Re: [PATCH] x86/bugs: KVM: Add support for SRSO_MSR_FIX To: "Borislav Petkov" Cc: "Sean Christopherson" , "Patrick Bellasi" , "Paolo Bonzini" , "Josh Poimboeuf" , "Pawan Gupta" , x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, "Patrick Bellasi" , "Brendan Jackman" In-Reply-To: <20250217202048.GIZ7OaIOWLH9Y05U-D@fat_crate.local> References: <20250213142815.GBZ64Bf3zPIay9nGza@fat_crate.local> <20250213175057.3108031-1-derkling@google.com> <20250214201005.GBZ6-jHUff99tmkyBK@fat_crate.local> <20250215125307.GBZ7COM-AkyaF8bNiC@fat_crate.local> <20250217160728.GFZ7NewJHpMaWdiX2M@fat_crate.local> <20250217202048.GIZ7OaIOWLH9Y05U-D@fat_crate.local> X-Migadu-Flow: FLOW_OUT February 17, 2025 at 12:20 PM, "Borislav Petkov" wrote: >=20 >=20On Mon, Feb 17, 2025 at 11:56:22AM -0800, Yosry Ahmed wrote: >=20 >=20>=20 >=20> I meant IBPB + MSR clear before going to userspace, or IBPB + MSR c= lear > > before a context switch. > >=20 >=20 > Basically what I said already: >=20 >=20"Yes, let's keep it simple and do anything more involved *only* if it= is > really necessary." Right, I agree as I mentioned earlier (assuming the perf hit is 1-2%), ju= st wanted to clarify what I meant.