From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (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 42C7E4C9B for ; Wed, 31 Jan 2024 01:13:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706663584; cv=none; b=amd4BNxSZx/ec2CWL3MK8iZchHYAdGlymxfeIn24+jfPVHXowofz38LiMcwtfMWslEdcO9URX9LBTYGIZQZZ+KLAO01GOMiOIQsO57odf0K+C+H2/kdB6EoHL8Ak0x2SOvbeGIvZHt8zNBsD/kW6paMGNASWgSFMEd206zFsEn4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706663584; c=relaxed/simple; bh=WnaiMYjG3HYrBPVosKeochjRi58QHb85b9Uafy87v5A=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=XwQGKRk8sjpE1P6np5WqkLqmgf5IxU4kIUkQ1m/erTPQrd0/EWB9SPYhH6KYidX2KihHyPlrmK8F8hj+z9mKnZzAsHG94IQtezegteoeDPLArv3weDAUAaUjw9YMEHC1A2Xv4JKlbXStwRHb07UUFvdeKYeBbX1ZIgi5eUslv2o= 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=bxtUb0Ti; arc=none smtp.client-ip=209.85.214.202 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="bxtUb0Ti" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-1d91d4c6469so6244435ad.0 for ; Tue, 30 Jan 2024 17:13:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1706663582; x=1707268382; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=/GoosJvXV4tQVgQnoX094ue9LgaeDV/puMZ+zgV5v8A=; b=bxtUb0TiHwOmU6maPYHXIhvFmIYpd50MHPIav0HTh/Nlrav1Fy1GGJ6RtF+v7+npPx 2OutdRlvUutzGPrSdtbWWN6KzEmANSTAj3r9lA5lW/HxltwtqO1XXlr5iCA2sngyKBec P0q8UFbLLhbTTVS9vnjzvMjIkulK4mau/oFu8a0kHSTA6VCnNT/VfhI8lgr/EGHcz15F NaD/EI38SVfL7ZRcg3vuI2KZJo2LQmHMLDgCkqM7dpSjebEN/V5+LB0X6p3AAiVhiOka 1qirr5pnuia0xUVd/ANL7VXSs/GrTcFIwm/gsqdkfPl1wZ6q9bnu/F2X9WfAXmxt6hcI j4Iw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706663582; x=1707268382; 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=/GoosJvXV4tQVgQnoX094ue9LgaeDV/puMZ+zgV5v8A=; b=dHpjn0LAMLGc463ztAf00OLlLRTl1u9UG0WSvk+HsjezWXr0FCkLxxVdebRkqjUcf6 LbQba0IuQEQnWPcqBAm61BD72fs4UgecMZYHNhE5pSYNxIjry+DbqubLQPjzRurcCroq 7bQ7q2DLDUEHnlnuQWL8fjvUEgYA6QETwzrulx1fhDb+Cz2QJzcZse2wMCC9h3ynrvIT CQVLwKM99Mivn+R403HZ1LMAd/GruliRnpO+6djq5VKRM1Kh0OxG+rFJCyyRVqO3DOvH voL6XRx9V6vv27TIBm+DgfAauYJnF7i/o5wpUr52/21TwUuSvNqgtH76a7VkposMK/oU AGGg== X-Gm-Message-State: AOJu0YwVBifGNhwB4Y6U2FtwRSSCqPlLawjAz90vQ60UbCLFTqzqO7GW Anp2TNZFyhodfhyub/tqkBAaVsxjTBdEm4h4FV1wFwlJiJ6OLh8OHt7PVnwYLanaGjtzhSjgrDv jeA== X-Google-Smtp-Source: AGHT+IHXA4t0uhZ7tzthJIqQkUlU7edO5hP5ya6T+NaNmVk8RFxp+26SnKPKNqGEdvTVdg4s3sxwKV4qvvQ= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a17:902:d212:b0:1d9:1e1:76ca with SMTP id t18-20020a170902d21200b001d901e176camr715ply.10.1706663582547; Tue, 30 Jan 2024 17:13:02 -0800 (PST) Date: Tue, 30 Jan 2024 17:13:00 -0800 In-Reply-To: <20231016115028.996656-9-michael.roth@amd.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20231016115028.996656-1-michael.roth@amd.com> <20231016115028.996656-9-michael.roth@amd.com> Message-ID: Subject: Re: [PATCH RFC gmem v1 8/8] KVM: x86: Determine shared/private faults based on vm_type From: Sean Christopherson To: Michael Roth Cc: kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, pbonzini@redhat.com, isaku.yamahata@intel.com, ackerleytng@google.com, vbabka@suse.cz, ashish.kalra@amd.com, nikunj.dadhania@amd.com, jroedel@suse.de, pankaj.gupta@amd.com Content-Type: text/plain; charset="us-ascii" On Mon, Oct 16, 2023, Michael Roth wrote: > For KVM_X86_SNP_VM, only the PFERR_GUEST_ENC_MASK flag is needed to > determine with an #NPF is due to a private/shared access by the guest. > Implement that handling here. Also add handling needed to deal with > SNP guests which in some cases will make MMIO accesses with the > encryption bit. ... > @@ -4356,12 +4357,19 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > return RET_PF_EMULATE; > } > > - if (fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) { > + /* > + * In some cases SNP guests will make MMIO accesses with the encryption > + * bit set. Handle these via the normal MMIO fault path. > + */ > + if (!slot && private_fault && kvm_is_vm_type(vcpu->kvm, KVM_X86_SNP_VM)) > + private_fault = false; Why? This is inarguably a guest bug. > + if (private_fault != kvm_mem_is_private(vcpu->kvm, fault->gfn)) { > kvm_mmu_prepare_memory_fault_exit(vcpu, fault); > return -EFAULT; > } > > - if (fault->is_private) > + if (private_fault) > return kvm_faultin_pfn_private(vcpu, fault); > > async = false; > diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h > index 759c8b718201..e5b973051ad9 100644 > --- a/arch/x86/kvm/mmu/mmu_internal.h > +++ b/arch/x86/kvm/mmu/mmu_internal.h > @@ -251,6 +251,24 @@ struct kvm_page_fault { > > int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); > > +static bool kvm_mmu_fault_is_private(struct kvm *kvm, gpa_t gpa, u64 err) > +{ > + bool private_fault = false; > + > + if (kvm_is_vm_type(kvm, KVM_X86_SNP_VM)) { > + private_fault = !!(err & PFERR_GUEST_ENC_MASK); > + } else if (kvm_is_vm_type(kvm, KVM_X86_SW_PROTECTED_VM)) { > + /* > + * This handling is for gmem self-tests and guests that treat > + * userspace as the authority on whether a fault should be > + * private or not. > + */ > + private_fault = kvm_mem_is_private(kvm, gpa >> PAGE_SHIFT); > + } This can be more simply: if (kvm_is_vm_type(kvm, KVM_X86_SNP_VM)) return !!(err & PFERR_GUEST_ENC_MASK); if (kvm_is_vm_type(kvm, KVM_X86_SW_PROTECTED_VM)) return kvm_mem_is_private(kvm, gpa >> PAGE_SHIFT);