From patchwork Mon Jan 15 12:56:54 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Durrant X-Patchwork-Id: 13519654 Received: from mail.xenproject.org (mail.xenproject.org [104.130.215.37]) (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 63FAE17591; Mon, 15 Jan 2024 13:38:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=xen.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=xen.org header.i=@xen.org header.b="hosJBfok" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:MIME-Version:References: In-Reply-To:Message-Id:Date:Subject:To:From; bh=TQCkPB1sujZxJovh7KF/VJS4UU1Zw/7OzvD4MgUIPi4=; b=hosJBfokCUB4hYaVc0cTAgfawi Xe6ACqD7lPmUjcKElkdmvJID8ZVVTAll1bhOPDthGWJwpTmjQ4riQLO7ErVhrIIlx2UtvIxv+JiZz WyOnrovubvx7ueimwB411tT0CQC4xMM0n0mmI9WaEfwe8VPeOUIuPwGv+s+zGUbgF/YE=; Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1rPMXG-0002k9-DY; Mon, 15 Jan 2024 12:57:50 +0000 Received: from 54-240-197-231.amazon.com ([54.240.197.231] helo=REM-PW02S00X.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1rPMXG-0002kM-42; Mon, 15 Jan 2024 12:57:50 +0000 From: Paul Durrant To: Paolo Bonzini , Jonathan Corbet , Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , David Woodhouse , Paul Durrant , Shuah Khan , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v12 07/20] KVM: pfncache: include page offset in uhva and use it consistently Date: Mon, 15 Jan 2024 12:56:54 +0000 Message-Id: <20240115125707.1183-8-paul@xen.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240115125707.1183-1-paul@xen.org> References: <20240115125707.1183-1-paul@xen.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Paul Durrant Currently the pfncache page offset is sometimes determined using the gpa and sometimes the khva, whilst the uhva is always page-aligned. After a subsequent patch is applied the gpa will not always be valid so adjust the code to include the page offset in the uhva and use it consistently as the source of truth. Also, where a page-aligned address is required, use PAGE_ALIGN_DOWN() for clarity. No functional change intended. Signed-off-by: Paul Durrant Reviewed-by: David Woodhouse --- Cc: Sean Christopherson Cc: Paolo Bonzini Cc: David Woodhouse v8: - New in this version. --- virt/kvm/pfncache.c | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-) diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c index 0eeb034d0674..97eec8ee3449 100644 --- a/virt/kvm/pfncache.c +++ b/virt/kvm/pfncache.c @@ -48,10 +48,10 @@ bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len) if (!gpc->active) return false; - if (offset_in_page(gpc->gpa) + len > PAGE_SIZE) + if (gpc->generation != slots->generation || kvm_is_error_hva(gpc->uhva)) return false; - if (gpc->generation != slots->generation || kvm_is_error_hva(gpc->uhva)) + if (offset_in_page(gpc->uhva) + len > PAGE_SIZE) return false; if (!gpc->valid) @@ -119,7 +119,7 @@ static inline bool mmu_notifier_retry_cache(struct kvm *kvm, unsigned long mmu_s static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc) { /* Note, the new page offset may be different than the old! */ - void *old_khva = gpc->khva - offset_in_page(gpc->khva); + void *old_khva = (void *)PAGE_ALIGN_DOWN((uintptr_t)gpc->khva); kvm_pfn_t new_pfn = KVM_PFN_ERR_FAULT; void *new_khva = NULL; unsigned long mmu_seq; @@ -192,7 +192,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc) gpc->valid = true; gpc->pfn = new_pfn; - gpc->khva = new_khva + offset_in_page(gpc->gpa); + gpc->khva = new_khva + offset_in_page(gpc->uhva); /* * Put the reference to the _new_ pfn. The pfn is now tracked by the @@ -217,6 +217,7 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, bool unmap_old = false; unsigned long old_uhva; kvm_pfn_t old_pfn; + bool hva_change = false; void *old_khva; int ret; @@ -242,10 +243,10 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, } old_pfn = gpc->pfn; - old_khva = gpc->khva - offset_in_page(gpc->khva); - old_uhva = gpc->uhva; + old_khva = (void *)PAGE_ALIGN_DOWN((uintptr_t)gpc->khva); + old_uhva = PAGE_ALIGN_DOWN(gpc->uhva); - /* If the userspace HVA is invalid, refresh that first */ + /* Refresh the userspace HVA if necessary */ if (gpc->gpa != gpa || gpc->generation != slots->generation || kvm_is_error_hva(gpc->uhva)) { gfn_t gfn = gpa_to_gfn(gpa); @@ -259,13 +260,25 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, ret = -EFAULT; goto out; } + + /* + * Even if the GPA and/or the memslot generation changed, the + * HVA may still be the same. + */ + if (gpc->uhva != old_uhva) + hva_change = true; + } else { + gpc->uhva = old_uhva; } + /* Note: the offset must be correct before calling hva_to_pfn_retry() */ + gpc->uhva += page_offset; + /* * If the userspace HVA changed or the PFN was already invalid, * drop the lock and do the HVA to PFN lookup again. */ - if (!gpc->valid || old_uhva != gpc->uhva) { + if (!gpc->valid || hva_change) { ret = hva_to_pfn_retry(gpc); } else { /*