From mboxrd@z Thu Jan 1 00:00:00 1970 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 61618C433FE for ; Fri, 4 Nov 2022 02:33:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 80F3D6B0071; Thu, 3 Nov 2022 22:33:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7BEE16B0073; Thu, 3 Nov 2022 22:33:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 686776B0074; Thu, 3 Nov 2022 22:33:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 5A8A96B0071 for ; Thu, 3 Nov 2022 22:33:33 -0400 (EDT) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 2635480150 for ; Fri, 4 Nov 2022 02:33:33 +0000 (UTC) X-FDA: 80094188706.09.1871803 Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by imf29.hostedemail.com (Postfix) with ESMTP id CFCD2120002 for ; Fri, 4 Nov 2022 02:33:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1667529212; x=1699065212; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=k6zHr8AHLwaL1LJlPryMMAsPTZ/apPmng/dSTG4NLmw=; b=NCRTCwvJy6hBsoUrd5YaGjx88Zu0x2T1PJXYuICIb+3WnsKUzyvs/jnZ cGXSPGwIdnA4aFxJYWVh/G0F9RMtcQhRb08PpaVO5/ypRw8SawdGslVwn T+N0EOQ8Vg0cW9Qs8STI9M/ZHAEXvvSA3Oxm0gEFRwWg27W+YatP7AWBX ZMPkHU3Rk8RvmoX60YnGq1MOEQ7jeOoIg42pJVDRMvPkX1Pk5t7oTyDn1 3nEeNOolYuE8T4nQj+CvgX5bHMciPbrSi7VT7BbL70w4aAQGY/lPdvsg6 0MViCb8oIjUzJwA4bbcimZLnrPbuak1PeGOELt+7IN+Qh2JPjKBttc6uK g==; X-IronPort-AV: E=McAfee;i="6500,9779,10520"; a="290249987" X-IronPort-AV: E=Sophos;i="5.96,135,1665471600"; d="scan'208";a="290249987" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Nov 2022 19:32:52 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10520"; a="666205484" X-IronPort-AV: E=Sophos;i="5.96,135,1665471600"; d="scan'208";a="666205484" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.193.75]) by orsmga008.jf.intel.com with ESMTP; 03 Nov 2022 19:32:41 -0700 Date: Fri, 4 Nov 2022 10:28:13 +0800 From: Chao Peng To: Fuad Tabba Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, Paolo Bonzini , Jonathan Corbet , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Shuah Khan , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , Michael Roth , mhocko@suse.com, Muchun Song , wei.w.wang@intel.com Subject: Re: [PATCH v9 4/8] KVM: Use gfn instead of hva for mmu_notifier_retry Message-ID: <20221104022813.GA4129873@chaop.bj.intel.com> Reply-To: Chao Peng References: <20221025151344.3784230-1-chao.p.peng@linux.intel.com> <20221025151344.3784230-5-chao.p.peng@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667529212; a=rsa-sha256; cv=none; b=rAmFiefJcdHqKw5yOEv25ukfCpPiGS7G/B494/+ZEHLrKZA7k7dZf3Olkdve8bVzuHkfgq DI780olQvkO4f+UEd5P1D2jSif8omZhFA1zGfg473xjEOeH5GVxw4o6D89EOoAKXkbvxEA 2DB6V8ooCoH7kNbhTQqu+FAf7prjwz0= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=NCRTCwvJ; spf=none (imf29.hostedemail.com: domain of chao.p.peng@linux.intel.com has no SPF policy when checking 192.55.52.151) smtp.mailfrom=chao.p.peng@linux.intel.com; dmarc=fail reason="No valid SPF" header.from=intel.com (policy=none) ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667529212; h=from:from:sender:reply-to: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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=htrlWJRg3+8FixjvppeSc9LYP89eTEkEmJ/K6iGx5Uw=; b=z5yHFbvQ8jIzQavtGhcrj0xpXsKC3/AX9hLcQW1HZQf3yGF1fwhlCAZhOWJ3rQA3w7DmbW ZsyyzWxQRlAo1ghpcHihZlfyeAxfUNr18wwI1AZi1h1YKtOWTvPOJD0fsNnKWDFo2C5pA/ e5Yk+LcCjhWPSCU20KiIh+0ucoLd/RY= X-Stat-Signature: bby5c58q1w43rbhec7z97xss1hawrfpw X-Rspamd-Server: rspam09 X-Rspam-User: X-Rspamd-Queue-Id: CFCD2120002 Authentication-Results: imf29.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=NCRTCwvJ; spf=none (imf29.hostedemail.com: domain of chao.p.peng@linux.intel.com has no SPF policy when checking 192.55.52.151) smtp.mailfrom=chao.p.peng@linux.intel.com; dmarc=fail reason="No valid SPF" header.from=intel.com (policy=none) X-HE-Tag: 1667529211-624053 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Oct 27, 2022 at 11:29:14AM +0100, Fuad Tabba wrote: > Hi, > > On Tue, Oct 25, 2022 at 4:19 PM Chao Peng wrote: > > > > Currently in mmu_notifier validate path, hva range is recorded and then > > checked against in the mmu_notifier_retry_hva() of the page fault path. > > However, for the to be introduced private memory, a page fault may not > > have a hva associated, checking gfn(gpa) makes more sense. > > > > For existing non private memory case, gfn is expected to continue to > > work. The only downside is when aliasing multiple gfns to a single hva, > > the current algorithm of checking multiple ranges could result in a much > > larger range being rejected. Such aliasing should be uncommon, so the > > impact is expected small. > > > > It also fixes a bug in kvm_zap_gfn_range() which has already been using > > nit: Now it's kvm_unmap_gfn_range(). Forgot to mention: the bug is still with kvm_zap_gfn_range(). It calls kvm_mmu_invalidate_begin/end with a gfn range but before this series kvm_mmu_invalidate_begin/end actually accept a hva range. Note it's unrelated to whether we use kvm_zap_gfn_range() or kvm_unmap_gfn_range() in the following patch (patch 05). Thanks, Chao > > > gfn when calling kvm_mmu_invalidate_begin/end() while these functions > > accept hva in current code. > > > > Signed-off-by: Chao Peng > > --- > > Based on reading this code and my limited knowledge of the x86 MMU code: > Reviewed-by: Fuad Tabba > > Cheers, > /fuad > > > > arch/x86/kvm/mmu/mmu.c | 2 +- > > include/linux/kvm_host.h | 18 +++++++--------- > > virt/kvm/kvm_main.c | 45 ++++++++++++++++++++++++++-------------- > > 3 files changed, 39 insertions(+), 26 deletions(-) > > > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > > index 6f81539061d6..33b1aec44fb8 100644 > > --- a/arch/x86/kvm/mmu/mmu.c > > +++ b/arch/x86/kvm/mmu/mmu.c > > @@ -4217,7 +4217,7 @@ static bool is_page_fault_stale(struct kvm_vcpu *vcpu, > > return true; > > > > return fault->slot && > > - mmu_invalidate_retry_hva(vcpu->kvm, mmu_seq, fault->hva); > > + mmu_invalidate_retry_gfn(vcpu->kvm, mmu_seq, fault->gfn); > > } > > > > static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > > index 739a7562a1f3..79e5cbc35fcf 100644 > > --- a/include/linux/kvm_host.h > > +++ b/include/linux/kvm_host.h > > @@ -775,8 +775,8 @@ struct kvm { > > struct mmu_notifier mmu_notifier; > > unsigned long mmu_invalidate_seq; > > long mmu_invalidate_in_progress; > > - unsigned long mmu_invalidate_range_start; > > - unsigned long mmu_invalidate_range_end; > > + gfn_t mmu_invalidate_range_start; > > + gfn_t mmu_invalidate_range_end; > > #endif > > struct list_head devices; > > u64 manual_dirty_log_protect; > > @@ -1365,10 +1365,8 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc); > > void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc); > > #endif > > > > -void kvm_mmu_invalidate_begin(struct kvm *kvm, unsigned long start, > > - unsigned long end); > > -void kvm_mmu_invalidate_end(struct kvm *kvm, unsigned long start, > > - unsigned long end); > > +void kvm_mmu_invalidate_begin(struct kvm *kvm, gfn_t start, gfn_t end); > > +void kvm_mmu_invalidate_end(struct kvm *kvm, gfn_t start, gfn_t end); > > > > long kvm_arch_dev_ioctl(struct file *filp, > > unsigned int ioctl, unsigned long arg); > > @@ -1937,9 +1935,9 @@ static inline int mmu_invalidate_retry(struct kvm *kvm, unsigned long mmu_seq) > > return 0; > > } > > > > -static inline int mmu_invalidate_retry_hva(struct kvm *kvm, > > +static inline int mmu_invalidate_retry_gfn(struct kvm *kvm, > > unsigned long mmu_seq, > > - unsigned long hva) > > + gfn_t gfn) > > { > > lockdep_assert_held(&kvm->mmu_lock); > > /* > > @@ -1949,8 +1947,8 @@ static inline int mmu_invalidate_retry_hva(struct kvm *kvm, > > * positives, due to shortcuts when handing concurrent invalidations. > > */ > > if (unlikely(kvm->mmu_invalidate_in_progress) && > > - hva >= kvm->mmu_invalidate_range_start && > > - hva < kvm->mmu_invalidate_range_end) > > + gfn >= kvm->mmu_invalidate_range_start && > > + gfn < kvm->mmu_invalidate_range_end) > > return 1; > > if (kvm->mmu_invalidate_seq != mmu_seq) > > return 1; > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > > index 8dace78a0278..09c9cdeb773c 100644 > > --- a/virt/kvm/kvm_main.c > > +++ b/virt/kvm/kvm_main.c > > @@ -540,8 +540,7 @@ static void kvm_mmu_notifier_invalidate_range(struct mmu_notifier *mn, > > > > typedef bool (*hva_handler_t)(struct kvm *kvm, struct kvm_gfn_range *range); > > > > -typedef void (*on_lock_fn_t)(struct kvm *kvm, unsigned long start, > > - unsigned long end); > > +typedef void (*on_lock_fn_t)(struct kvm *kvm, gfn_t start, gfn_t end); > > > > typedef void (*on_unlock_fn_t)(struct kvm *kvm); > > > > @@ -628,7 +627,8 @@ static __always_inline int __kvm_handle_hva_range(struct kvm *kvm, > > locked = true; > > KVM_MMU_LOCK(kvm); > > if (!IS_KVM_NULL_FN(range->on_lock)) > > - range->on_lock(kvm, range->start, range->end); > > + range->on_lock(kvm, gfn_range.start, > > + gfn_range.end); > > if (IS_KVM_NULL_FN(range->handler)) > > break; > > } > > @@ -715,15 +715,9 @@ static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn, > > kvm_handle_hva_range(mn, address, address + 1, pte, kvm_set_spte_gfn); > > } > > > > -void kvm_mmu_invalidate_begin(struct kvm *kvm, unsigned long start, > > - unsigned long end) > > +static inline void update_invalidate_range(struct kvm *kvm, gfn_t start, > > + gfn_t end) > > { > > - /* > > - * The count increase must become visible at unlock time as no > > - * spte can be established without taking the mmu_lock and > > - * count is also read inside the mmu_lock critical section. > > - */ > > - kvm->mmu_invalidate_in_progress++; > > if (likely(kvm->mmu_invalidate_in_progress == 1)) { > > kvm->mmu_invalidate_range_start = start; > > kvm->mmu_invalidate_range_end = end; > > @@ -744,6 +738,28 @@ void kvm_mmu_invalidate_begin(struct kvm *kvm, unsigned long start, > > } > > } > > > > +static void mark_invalidate_in_progress(struct kvm *kvm, gfn_t start, gfn_t end) > > +{ > > + /* > > + * The count increase must become visible at unlock time as no > > + * spte can be established without taking the mmu_lock and > > + * count is also read inside the mmu_lock critical section. > > + */ > > + kvm->mmu_invalidate_in_progress++; > > +} > > + > > +static bool kvm_mmu_handle_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) > > +{ > > + update_invalidate_range(kvm, range->start, range->end); > > + return kvm_unmap_gfn_range(kvm, range); > > +} > > + > > +void kvm_mmu_invalidate_begin(struct kvm *kvm, gfn_t start, gfn_t end) > > +{ > > + mark_invalidate_in_progress(kvm, start, end); > > + update_invalidate_range(kvm, start, end); > > +} > > + > > static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, > > const struct mmu_notifier_range *range) > > { > > @@ -752,8 +768,8 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, > > .start = range->start, > > .end = range->end, > > .pte = __pte(0), > > - .handler = kvm_unmap_gfn_range, > > - .on_lock = kvm_mmu_invalidate_begin, > > + .handler = kvm_mmu_handle_gfn_range, > > + .on_lock = mark_invalidate_in_progress, > > .on_unlock = kvm_arch_guest_memory_reclaimed, > > .flush_on_ret = true, > > .may_block = mmu_notifier_range_blockable(range), > > @@ -791,8 +807,7 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, > > return 0; > > } > > > > -void kvm_mmu_invalidate_end(struct kvm *kvm, unsigned long start, > > - unsigned long end) > > +void kvm_mmu_invalidate_end(struct kvm *kvm, gfn_t start, gfn_t end) > > { > > /* > > * This sequence increase will notify the kvm page fault that > > -- > > 2.25.1 > >