From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f202.google.com (mail-yw1-f202.google.com [209.85.128.202]) (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 DCE881C68F for ; Thu, 7 Mar 2024 14:36:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709822171; cv=none; b=KUtLUGPO7oPtIScDi9sxy4Wu1EE+W2KmOUsHzTaBJ3+z4L5gnHOxtDd+HdRgsO6Ii6Xk4NxO/eeTTHGlJ0Q9EYjckAdv1NPq77NDpEohLERSDBPcNZmiDDz4E72Em7dyY1WhVH2YscX1ccJ/FkXe6HNv+mrumyD0FDR9GvOLdpY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709822171; c=relaxed/simple; bh=5c2pdnlbWCYsX5AL6tAQ6PuzfWITspmp5cYuOF4KTUg=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=uTwbH2IGw69lnMRgpTGXCiyseiqqOs/mn+zO+2Kdq25Kx8UsPCOjOZ8MNDJ8D5PDjiXtyRztfuMDQrBy6OwNcftvoCiX8SmTWskU3M/mqumIpbRPZEsg997FJ6Dn7xA8kMjq7XTseuV5J53jOO477cnOW+lKcb7aMw+RVEWipZI= 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=KOwv1gkT; arc=none smtp.client-ip=209.85.128.202 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="KOwv1gkT" Received: by mail-yw1-f202.google.com with SMTP id 00721157ae682-608ad239f8fso17132177b3.0 for ; Thu, 07 Mar 2024 06:36:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1709822169; x=1710426969; 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=uQkndU5MaQMQimAlXbJ2bKIU8av7qyfvd42xkrItWQQ=; b=KOwv1gkT34HkiFNiGgwW3I7Siwb8jdEV/eEP/tTXJP9R1EhMpAAa5x24qFnk+joyOQ NM7Nc68HZRj6f6PTA2ZE6/M5qQ+2/6r4ULBsTxfVopx/xTGl3L1Os4DXY3S1atmlVWyP 2A5X+iYOW4dtgH7TtSnb6cImEhYr9X4abrFmVzITP6O3Pw+h320s8jJa2qs0JakH1tqU qd/DW9Y26PEts76gL5pwfYC21frDGxffWYqvE4jQ6JgVvC76SRBh2mNGqgXGkpfLbC8J xaeMCJcEUyxGuZtwnsm4OAO7ejY+jlAjUiTauthyEVzmirSCVKlXF3c+p1Pl8nIOocnC 2LtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1709822169; x=1710426969; 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=uQkndU5MaQMQimAlXbJ2bKIU8av7qyfvd42xkrItWQQ=; b=fWPeU/5vp3LFsLtSKPBwl3V8rtQId8M5j+HepCK1XEAL8303xGYHvghL+GB+tBsyW6 NpzX2JBBjWE9sJc48qqJUmMoMn0+Fr1th0XrMQvXOYjMlhPjbjSgH0JC8d+JPEXDzVu/ j8V8+Lq+uOtgtiTu+hYwrSupFeX++dCsnhOxRpagwtnBtPdGEgEMhcZLEd2XEa3FIbzD 6XljMWP1SMDWzYkO4KiOfdS2JSn5U4ZwJkoDwjighH7aLjmFWDhpwJD5LnDwIXHYrWeO 4ie32Ei4AW9PsoY1hQ+qAoI6bGfLPFvzGrogAuwC8f2ZB8DuARn7hWA1tRvGU48tRbWL OzZg== X-Forwarded-Encrypted: i=1; AJvYcCX5o5ETQs3eLOiZuYxb/P5ImPizDKUVKlDKoSTjfR8y/dQS+sbD2m+PDOORDWk9dPxFwkb4spLBzSD5T5MjGIC1G4wI X-Gm-Message-State: AOJu0YzerxcAzCwz6kZImi8FEjMRkp7V3GDpOnE8yFBu/OAn2eCZUpLL WDcJJuinqAiAze9PtseKOSRHlr6fuKNq62POK+WfBm6HTt9UDMcYDccDi9DiP/fPLqJcztlq2SM YQg== X-Google-Smtp-Source: AGHT+IFES2CcpL5jNV0bCQu5D8bKAvGmHTylSGvybuc45Nl4UwGQmVKoE4uXkDOBCpzqshSi3hTNjQCdGGY= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6902:18c7:b0:dcc:6065:2b3d with SMTP id ck7-20020a05690218c700b00dcc60652b3dmr4413088ybb.8.1709822168860; Thu, 07 Mar 2024 06:36:08 -0800 (PST) Date: Thu, 7 Mar 2024 06:36:07 -0800 In-Reply-To: Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240228024147.41573-1-seanjc@google.com> <20240228024147.41573-6-seanjc@google.com> Message-ID: Subject: Re: [PATCH 05/16] KVM: x86/mmu: Use synthetic page fault error code to indicate private faults From: Sean Christopherson To: Xu Yilun Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Yan Zhao , Isaku Yamahata , Michael Roth , Yu Zhang , Chao Peng , Fuad Tabba , David Matlack Content-Type: text/plain; charset="us-ascii" On Thu, Mar 07, 2024, Xu Yilun wrote: > On Wed, Mar 06, 2024 at 06:45:30AM -0800, Sean Christopherson wrote: > > can be switched between private and shared, e.g. will return false for > > kvm_arch_has_private_mem(). > > > > And KVM _can't_ sanely use private/shared memslots for SEV(-ES), because it's > > impossible to intercept implicit conversions by the guest, i.e. KVM can't prevent > > the guest from encrypting a page that KVM thinks is private, and vice versa. > > Is it because there is no #NPF for RMP violation? Yep, there is no RMP, thus no way for the host to express its view of shared vs. private to hardware. As a result, KVM can't block conversions, and the given state of a page is completely unkown at any given time. E.g. when memory is reclaimed from an SEV(-ES) guest, KVM has to assume that the page is encrypted and thus needs to be flushed (see sev_guest_memory_reclaimed()).