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([2001:b07:6468:f312:7822:aa18:a9d8:39ab]) by smtp.gmail.com with ESMTPSA id o20sm32957541wrh.8.2019.06.24.03.12.25 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Mon, 24 Jun 2019 03:12:26 -0700 (PDT) To: Peter Xu , qemu-devel@nongnu.org References: <20190624091811.30412-1-peterx@redhat.com> <20190624091811.30412-3-peterx@redhat.com> From: Paolo Bonzini Message-ID: <53a519b1-a514-8a07-c17e-0c704cfe6d26@redhat.com> Date: Mon, 24 Jun 2019 12:12:25 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190624091811.30412-3-peterx@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.85.128.66 Subject: Re: [Qemu-devel] [PATCH v2 2/2] intel_iommu: Fix unexpected unmaps during global unmap X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Auger Eric , Jason Wang , Yan Zhao , "Michael S . Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 24/06/19 11:18, Peter Xu wrote: > This is an replacement work of Yan Zhao's patch: > > https://www.mail-archive.com/qemu-devel@nongnu.org/msg625340.html > > vtd_address_space_unmap() will do proper page mask alignment to make > sure each IOTLB message will have correct masks for notification > messages (2^N-1), but sometimes it can be expanded to even supercede > the registered range. That could lead to unexpected UNMAP of already > mapped regions in some other notifiers. > > Instead of doing mindless expension of the start address and address > mask, we split the range into smaller ones and guarantee that each > small range will have correct masks (2^N-1) and at the same time we > should also try our best to generate as less IOTLB messages as > possible. > > Reported-by: Yan Zhao > Signed-off-by: Peter Xu > --- > hw/i386/intel_iommu.c | 67 ++++++++++++++++++++++++++----------------- > 1 file changed, 41 insertions(+), 26 deletions(-) > > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c > index 719ce19ab3..de86f53b4e 100644 > --- a/hw/i386/intel_iommu.c > +++ b/hw/i386/intel_iommu.c > @@ -3363,11 +3363,28 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, PCIBus *bus, int devfn) > return vtd_dev_as; > } > > +static uint64_t get_naturally_aligned_size(uint64_t start, > + uint64_t size, int gaw) > +{ > + uint64_t max_mask = 1ULL << gaw; > + uint64_t alignment = start ? start & -start : max_mask; > + > + alignment = MIN(alignment, max_mask); > + size = MIN(size, max_mask); > + > + if (alignment <= size) { > + /* Increase the alignment of start */ > + return alignment; > + } else { > + /* Find the largest page mask from size */ > + return 1ULL << (63 - clz64(size)); > + } > +} > + > /* Unmap the whole range in the notifier's scope. */ > static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n) > { > - IOMMUTLBEntry entry; > - hwaddr size; > + hwaddr size, remain; > hwaddr start = n->start; > hwaddr end = n->end; > IntelIOMMUState *s = as->iommu_state; > @@ -3388,39 +3405,37 @@ static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n) > } > > assert(start <= end); > - size = end - start; > + size = remain = end - start + 1; > > - if (ctpop64(size) != 1) { > - /* > - * This size cannot format a correct mask. Let's enlarge it to > - * suite the minimum available mask. > - */ > - int n = 64 - clz64(size); > - if (n > s->aw_bits) { > - /* should not happen, but in case it happens, limit it */ > - n = s->aw_bits; > - } > - size = 1ULL << n; > + while (remain >= VTD_PAGE_SIZE) { > + IOMMUTLBEntry entry; > + uint64_t mask = get_naturally_aligned_size(start, remain, s->aw_bits); > + > + assert(mask); > + > + entry.iova = start; > + entry.addr_mask = mask - 1; > + entry.target_as = &address_space_memory; > + entry.perm = IOMMU_NONE; > + /* This field is meaningless for unmap */ > + entry.translated_addr = 0; > + > + memory_region_notify_one(n, &entry); > + > + start += mask; > + remain -= mask; > } > > - entry.target_as = &address_space_memory; > - /* Adjust iova for the size */ > - entry.iova = n->start & ~(size - 1); > - /* This field is meaningless for unmap */ > - entry.translated_addr = 0; > - entry.perm = IOMMU_NONE; > - entry.addr_mask = size - 1; > + assert(!remain); > > trace_vtd_as_unmap_whole(pci_bus_num(as->bus), > VTD_PCI_SLOT(as->devfn), > VTD_PCI_FUNC(as->devfn), > - entry.iova, size); > + n->start, size); > > - map.iova = entry.iova; > - map.size = entry.addr_mask; > + map.iova = n->start; > + map.size = size; > iova_tree_remove(as->iova_tree, &map); > - > - memory_region_notify_one(n, &entry); > } > > static void vtd_address_space_unmap_all(IntelIOMMUState *s) > Looks good, ignore my previous message. Paolo