From patchwork Tue May 7 15:58:14 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13657381 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 974AF16C69E for ; Tue, 7 May 2024 15:58:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715097507; cv=none; b=cUeABQNoXBS43THyJrFdy0osMVpTeCTY8RL7y35SSLXOxHYj6qXEGg1fNy1YVoMdan/J4lQtN0AWxkiZaglWVFqlx/hNzU4fFGaGHKBzDqfK/0G4RqHeCrdTU0R2d3BR0zBECGxWzTWI4e5tv1z3Mv3ECE/nHBm+QeL0mSXHotg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715097507; c=relaxed/simple; bh=Nv7alPH5S+bfefJPfN/RIwSAyzbcD0z6//fULF1pSNg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=o8/igXfuPg5S0kk2q2UGz3lBrihxmBYAnL3ca7GcOJlckMu5R2NU4QLg7NAe3sqh3Fuw9eiJTLMNrkwrgM2fup25k97yrbjHmjpe8SgFBDQrau08IegqmgW4dV6S7KKHXdJOarcciHEFZvHrdsxLae1c1RHRk5AOEcn2EICHZmI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=M9WCl8WZ; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="M9WCl8WZ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1715097503; 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=B008ipLLAUODyL5/aCau7+Mv2sC3RQCFlbYlFbvm7+c=; b=M9WCl8WZ+rzQsbrJ9NWCO8xKVw0vLxm1QajFb3FrPDqAhB7gfkSCD2f0am5yWqBaV1pJdo gQBoqTdnOgrkyPx+IT9dLg+2kyGZGaKbISynVTD7+RY4UYzleCzUdlsFoEGdfcLa5l/EIy eA91dTquEznr4n6QAeWmK5+Fubepyps= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-279-Whl3HQ72PNaa1_RSdPwmTw-1; Tue, 07 May 2024 11:58:21 -0400 X-MC-Unique: Whl3HQ72PNaa1_RSdPwmTw-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8D62B857A86; Tue, 7 May 2024 15:58:20 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 670074750A1; Tue, 7 May 2024 15:58:20 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Sean Christopherson , David Matlack , Kai Huang Subject: [PATCH 14/17] KVM: x86/mmu: Handle no-slot faults at the beginning of kvm_faultin_pfn() Date: Tue, 7 May 2024 11:58:14 -0400 Message-ID: <20240507155817.3951344-15-pbonzini@redhat.com> In-Reply-To: <20240507155817.3951344-1-pbonzini@redhat.com> References: <20240507155817.3951344-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 From: Sean Christopherson Handle the "no memslot" case at the beginning of kvm_faultin_pfn(), just after the private versus shared check, so that there's no need to repeatedly query whether or not a slot exists. This also makes it more obvious that, except for private vs. shared attributes, the process of faulting in a pfn simply doesn't apply to gfns without a slot. Opportunistically stuff @fault's metadata in kvm_handle_noslot_fault() so that it doesn't need to be duplicated in all paths that invoke kvm_handle_noslot_fault(), and to minimize the probability of not stuffing the right fields. Leave the existing handle behind, but convert it to a WARN, to guard against __kvm_faultin_pfn() unexpectedly nullifying fault->slot. Cc: David Matlack Signed-off-by: Sean Christopherson Reviewed-by: Kai Huang Message-ID: <20240228024147.41573-14-seanjc@google.com> Signed-off-by: Paolo Bonzini Reviewed-by: Xiaoyao Li --- arch/x86/kvm/mmu/mmu.c | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index b09c8034ed15..7630ad8cb022 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3270,6 +3270,10 @@ static int kvm_handle_noslot_fault(struct kvm_vcpu *vcpu, vcpu_cache_mmio_info(vcpu, gva, fault->gfn, access & shadow_mmio_access_mask); + fault->slot = NULL; + fault->pfn = KVM_PFN_NOSLOT; + fault->map_writable = false; + /* * If MMIO caching is disabled, emulate immediately without * touching the shadow page tables as attempting to install an @@ -4350,15 +4354,18 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, return -EFAULT; } + if (unlikely(!slot)) + return kvm_handle_noslot_fault(vcpu, fault, access); + /* * Retry the page fault if the gfn hit a memslot that is being deleted * or moved. This ensures any existing SPTEs for the old memslot will * be zapped before KVM inserts a new MMIO SPTE for the gfn. */ - if (slot && (slot->flags & KVM_MEMSLOT_INVALID)) + if (slot->flags & KVM_MEMSLOT_INVALID) return RET_PF_RETRY; - if (slot && slot->id == APIC_ACCESS_PAGE_PRIVATE_MEMSLOT) { + if (slot->id == APIC_ACCESS_PAGE_PRIVATE_MEMSLOT) { /* * Don't map L1's APIC access page into L2, KVM doesn't support * using APICv/AVIC to accelerate L2 accesses to L1's APIC, @@ -4370,12 +4377,9 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, * uses different roots for L1 vs. L2, i.e. there is no danger * of breaking APICv/AVIC for L1. */ - if (is_guest_mode(vcpu)) { - fault->slot = NULL; - fault->pfn = KVM_PFN_NOSLOT; - fault->map_writable = false; - goto faultin_done; - } + if (is_guest_mode(vcpu)) + return kvm_handle_noslot_fault(vcpu, fault, access); + /* * If the APIC access page exists but is disabled, go directly * to emulation without caching the MMIO access or creating a @@ -4386,6 +4390,9 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, return RET_PF_EMULATE; } + fault->mmu_seq = vcpu->kvm->mmu_invalidate_seq; + smp_rmb(); + /* * Check for a relevant mmu_notifier invalidation event before getting * the pfn from the primary MMU, and before acquiring mmu_lock. @@ -4407,19 +4414,17 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, * *guaranteed* to need to retry, i.e. waiting until mmu_lock is held * to detect retry guarantees the worst case latency for the vCPU. */ - if (fault->slot && - mmu_invalidate_retry_gfn_unsafe(vcpu->kvm, fault->mmu_seq, fault->gfn)) + if (mmu_invalidate_retry_gfn_unsafe(vcpu->kvm, fault->mmu_seq, fault->gfn)) return RET_PF_RETRY; ret = __kvm_faultin_pfn(vcpu, fault); if (ret != RET_PF_CONTINUE) return ret; -faultin_done: if (unlikely(is_error_pfn(fault->pfn))) return kvm_handle_error_pfn(vcpu, fault); - if (unlikely(!fault->slot)) + if (WARN_ON_ONCE(!fault->slot)) return kvm_handle_noslot_fault(vcpu, fault, access); /*