From nobody Sun Sep 7 12:21:39 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 35FBECDB482 for ; Mon, 16 Oct 2023 16:40:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233517AbjJPQkX (ORCPT ); Mon, 16 Oct 2023 12:40:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41374 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343561AbjJPQjO (ORCPT ); Mon, 16 Oct 2023 12:39:14 -0400 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E767F76AE; Mon, 16 Oct 2023 09:22:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1697473375; x=1729009375; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=z79mJ2lGPPIhrYp3OMzu/977wMaINof4gRBego6+E/U=; b=QuDoBD2nIVqf2ETy+sNcI/2b3GnEU6pMBuKPYPxLErJvMXyzuFkydMsM 7ucZiLi0GqYrQ8FF13whAM21ILY9X50IPOn11gktnq2J5Fvjt7RCCrLMP 2bjUeUqNR2Qv5RRQ3SnHZkXczv8g9TjDsuOBXO18saT6VAAOXlr8gHs9s Q1fTI+yujLS4hAq6liCdmmeKm0eEoYQ9eEUQnmwk1ZoAPUyOV4DasFJro RqjThaduakEex2/hrSEkP6mBwwoftvfZEd9QHawUTe7BECfPZKgO/4fFt Kf7YUkQD1rlhSa0BlqvAVskW+cZdJ1TsYJ0iIsW67s5uL9Xw0oTLRJOaZ w==; X-IronPort-AV: E=McAfee;i="6600,9927,10865"; a="365826030" X-IronPort-AV: E=Sophos;i="6.03,229,1694761200"; d="scan'208";a="365826030" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Oct 2023 09:15:37 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10865"; a="1087126099" X-IronPort-AV: E=Sophos;i="6.03,229,1694761200"; d="scan'208";a="1087126099" Received: from ls.sc.intel.com (HELO localhost) ([172.25.112.31]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Oct 2023 09:15:35 -0700 From: isaku.yamahata@intel.com To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: isaku.yamahata@intel.com, isaku.yamahata@gmail.com, Paolo Bonzini , erdemaktas@google.com, Sean Christopherson , Sagi Shahar , David Matlack , Kai Huang , Zhi Wang , chen.bo@intel.com, hang.yuan@intel.com, tina.zhang@intel.com Subject: [PATCH v16 031/116] KVM: Allow page-sized MMU caches to be initialized with custom 64-bit values Date: Mon, 16 Oct 2023 09:13:43 -0700 Message-Id: X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Sean Christopherson Add support to MMU caches for initializing a page with a custom 64-bit value, e.g. to pre-fill an entire page table with non-zero PTE values. The functionality will be used by x86 to support Intel's TDX, which needs to set bit 63 in all non-present PTEs in order to prevent !PRESENT page faults from getting reflected into the guest (Intel's EPT Violation #VE architecture made the less than brilliant decision of having the per-PTE behavior be opt-out instead of opt-in). Signed-off-by: Sean Christopherson Signed-off-by: Isaku Yamahata --- include/linux/kvm_types.h | 1 + virt/kvm/kvm_main.c | 16 ++++++++++++++-- 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h index 9d1f7835d8c1..60c8d5c9eab9 100644 --- a/include/linux/kvm_types.h +++ b/include/linux/kvm_types.h @@ -94,6 +94,7 @@ struct gfn_to_pfn_cache { struct kvm_mmu_memory_cache { gfp_t gfp_zero; gfp_t gfp_custom; + u64 init_value; struct kmem_cache *kmem_cache; int capacity; int nobjs; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index aa9426472bb4..eb45bd2ca706 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -403,12 +403,17 @@ static void kvm_flush_shadow_all(struct kvm *kvm) static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache= *mc, gfp_t gfp_flags) { + void *page; + gfp_flags |=3D mc->gfp_zero; =20 if (mc->kmem_cache) return kmem_cache_alloc(mc->kmem_cache, gfp_flags); - else - return (void *)__get_free_page(gfp_flags); + + page =3D (void *)__get_free_page(gfp_flags); + if (page && mc->init_value) + memset64(page, mc->init_value, PAGE_SIZE / sizeof(mc->init_value)); + return page; } =20 int __kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int capa= city, int min) @@ -423,6 +428,13 @@ int __kvm_mmu_topup_memory_cache(struct kvm_mmu_memory= _cache *mc, int capacity, if (WARN_ON_ONCE(!capacity)) return -EIO; =20 + /* + * Custom init values can be used only for page allocations, + * and obviously conflict with __GFP_ZERO. + */ + if (WARN_ON_ONCE(mc->init_value && (mc->kmem_cache || mc->gfp_zero))) + return -EIO; + mc->objects =3D kvmalloc_array(sizeof(void *), capacity, gfp); if (!mc->objects) return -ENOMEM; --=20 2.25.1