From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (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 A096E14AD0D for ; Tue, 25 Feb 2025 15:41:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740498077; cv=none; b=X9KbbDxqAPCCs+DJW5IvUHuNIbEGR8GMrXq9R13gwo6KOW0DMR5p8KMK1l3dA8xrFr9i45HmWIxvycLNSq/JeKh/qBQHBGW3jyTzbQ/dmeOCpr9gAd7vjYjRq63OJjEFJpapxWCge9zO9+KSp7OHNCEq9sVXWsH6HIGvWYfKlAQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740498077; c=relaxed/simple; bh=h0k6Bw8oebc5YQIbZ75hirrCib3mxXfTLg5zcaiUPQU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=ezeq8L2k8CcahKqsVzDXTSS/eL9lrrQXMwXM9OkbkL/iXvY6CxTJtI2vcykKHcJRFXRD4ZV51a+9YWrKjQiZxuxe2Mbznk/q+modkYiq3HNadCwQPe8aw4V3mMnzPZxs/UpUV33MEcDfBKUrpdU9ktnTHZOMTaoMzA2pGeAvFJ0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=lvpEHwrX; arc=none smtp.client-ip=209.85.216.74 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--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="lvpEHwrX" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-2fc1a70935fso12005518a91.1 for ; Tue, 25 Feb 2025 07:41:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1740498075; x=1741102875; 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=9gith30kTBfPn10AwyFeCKv7JIoJKUJTfhcaJAgn5H8=; b=lvpEHwrXZMafR5bjJMMb/R0J7wbSws4Ye2WMk1fS+rUsdeN7iGm8r7jJsWa+4G+xoU Sz5T5bjLekDkQtOPdVnzZSHB96XbjTGvPeuQOv0BkT9rg3A2RejXPFEHNzp5zKaGhZEE ai+QMEI0cNmJwsv7CcO7O9wMkLRTBt9TCVAFqt9DibPPwcadBut8WasGHIZAejgbEiv1 eQ2z10bP+q9CDsnLIoPnS2VwmEwIQ5HxaW+s2TD/YvXzk+94xLq70MyfJmeL4R6/l/Vf qRd64KdU5RGPoXUkqEXVzeF5bvhWqWHqTZFyF4IH0ohtDAvkmXo9oLsLxssjMFTlIPz8 ABDg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740498075; x=1741102875; 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=9gith30kTBfPn10AwyFeCKv7JIoJKUJTfhcaJAgn5H8=; b=UvOFU9kTyW+Qt1I1EpxmDwb2yZtCY36/9KOmUX/im5XhVMnfMe7M6IYb9u6B6SB7qE TTNz8E1QKPbP0aBL42c5tP9qQwiS+0l26sbcpXQmeFE5MER3CyW25rlWsakQq4dTkfJn 7C6ucu0HVsI4vgpdO5h/SfJXy3mUW8uDk/Jy8YyP6Ohn2ZHwjLT63fEv4SphRR3pgNHD PGMn9etKs6qLWGfA6DovALiViXbYL/kLJ3aerIn069MVbq00/gfr5iUZ1QBREUNq8rrF 9pMBpcpRkf2TQKdAPibDjt4oNPRnnt6eYas7pHVogBgCtfAG8A+ZARb+pStKmWc+Gy6B 94ww== X-Gm-Message-State: AOJu0YyZO/MQAU2rbCpESCg9hgqDfDGcJRIhpvuSVocntCeWCyDiHbSB u771v+vTNPeM/8iK0ZiLhqq93RJ95TM9YqJ4hiopcZ/ixfUKs1Y3ggUk1OkSArtyooCIleLunV8 a3Q== X-Google-Smtp-Source: AGHT+IGZkp+roO0TVp3rz40ka6O9p/N9EvFel5/ggMinuedWjO6jtk5+r13X1rdCPxFnx16CfV0N9Na/IiI= X-Received: from pjbpv16.prod.google.com ([2002:a17:90b:3c90:b0:2fc:11a0:c53f]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:2e4f:b0:2f1:3355:4a8f with SMTP id 98e67ed59e1d1-2fe68ac94a8mr5754618a91.4.1740498074970; Tue, 25 Feb 2025 07:41:14 -0800 (PST) Date: Tue, 25 Feb 2025 07:41:13 -0800 In-Reply-To: <20241001050110.3643764-21-xin@zytor.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241001050110.3643764-1-xin@zytor.com> <20241001050110.3643764-21-xin@zytor.com> Message-ID: Subject: Re: [PATCH v3 20/27] KVM: x86: Allow WRMSRNS to be advertised to guests From: Sean Christopherson To: "Xin Li (Intel)" Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, pbonzini@redhat.com, corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, luto@kernel.org, peterz@infradead.org, andrew.cooper3@citrix.com Content-Type: text/plain; charset="us-ascii" On Mon, Sep 30, 2024, Xin Li (Intel) wrote: > From: Xin Li > > Allow WRMSRNS to be advertised to guests. The shortlog and this sentence are incorrect. Assuming there are no controls for WRMSRNS, then KVM isn't allowing anything. Userspace can advertise WRMSRNS support whenever it wants, and the guest can cleanly execute WRMSRNS regardless of whether or not it's advertised in CPUID. KVM is simply advertising support to userspace. > WRMSRNS behaves exactly like WRMSR with the only difference being Nope, not the only difference. WRMSR and WRMSRNS use the same basic exit reason (see Appendix C). For WRMSR, the exit qualification is 0, while for WRMSRNS it is 1. And the whole reaosn I went spelunking was to verify that WRMSRNS honors all MSR exiting controls and generates the same exits. That information needs to be explicitly stated. I'll rewrite the shortlog and changelog when applying.