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([2a01:e0a:59e:9d80:527b:9dff:feef:3874]) by smtp.gmail.com with ESMTPSA id g9-20020ae9e109000000b007678850233fsm965635qkm.66.2023.07.04.23.20.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 04 Jul 2023 23:20:02 -0700 (PDT) Message-ID: <1e6ae4e2-cd7c-16c4-440f-119399d0f551@redhat.com> Date: Wed, 5 Jul 2023 08:19:59 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Subject: Re: [PATCH 1/2] virtio-iommu: Fix 64kB host page size VFIO device assignment Content-Language: en-US To: "Duan, Zhenzhong" , "eric.auger.pro@gmail.com" , "qemu-devel@nongnu.org" , "qemu-arm@nongnu.org" , "mst@redhat.com" , "jean-philippe@linaro.org" Cc: "alex.williamson@redhat.com" , "clg@redhap.com" , "bharat.bhushan@nxp.com" , "peter.maydell@linaro.org" References: <20230704111527.3424992-1-eric.auger@redhat.com> <20230704111527.3424992-2-eric.auger@redhat.com> From: Eric Auger In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=eric.auger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.09, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: eric.auger@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hi Zhenzhong, On 7/5/23 06:52, Duan, Zhenzhong wrote: > Hi Eric, > >> -----Original Message----- >> From: Eric Auger >> Sent: Tuesday, July 4, 2023 7:15 PM >> Subject: [PATCH 1/2] virtio-iommu: Fix 64kB host page size VFIO device >> assignment >> >> When running on a 64kB page size host and protecting a VFIO device >> with the virtio-iommu, qemu crashes with this kind of message: >> >> qemu-kvm: virtio-iommu page mask 0xfffffffffffff000 is incompatible >> with mask 0x20010000 > Does 0x20010000 mean only 512MB and 64KB super page mapping is > supported for host iommu hw? 4KB mapping not supported? Yes that's correct. In that case the host has 64kB page and 4kB is not supported. > > There is a check in guest kernel side hint only 4KB is supported, with > this patch we force viommu->pgsize_bitmap to 0x20010000 > and fail below check? Does this device work in guest? > Please correct me if I understand wrong. my guest also has 64kB so the check hereafter succeeds. effectively in case your host has a larger page size than your guest it fails with [    2.147031] virtio-pci 0000:00:01.0: granule 0x10000 larger than system page size 0x1000 [    7.231128] ixgbevf 0000:00:02.0: granule 0x10000 larger than system page size 0x1000 > > static int viommu_domain_finalise(struct viommu_endpoint *vdev, > struct iommu_domain *domain) > { > ... > viommu_page_size = 1UL << __ffs(viommu->pgsize_bitmap); > if (viommu_page_size > PAGE_SIZE) { > dev_err(vdev->dev, > "granule 0x%lx larger than system page size 0x%lx\n", > viommu_page_size, PAGE_SIZE); > return -ENODEV; > } > > Another question is: Presume 0x20010000 does mean only 512MB and 64KB > is supported. Is host hva->hpa mapping ensured to be compatible with at least > 64KB mapping? If host mmu only support 4KB mapping or other non-compatible > with 0x20010000, will vfio_dma_map() fail? the page size mask is retrieved with VFIO_IOMMU_GET_INFO uapi which returns host vfio_iommu_type1 vfio_iommu->pgsize_bitmap. This latter is initialized to host PAGE_MASK and later restricted on vfio_iommu_type1_attach_group though the vfio_update_pgsize_bitmap() calls so yes both IOMMU and CPU page size are garanteed to be compatible. > >> qemu: hardware error: vfio: DMA mapping failed, unable to continue >> >> This is due to the fact the IOMMU MR corresponding to the VFIO device >> is enabled very late on domain attach, after the machine init. >> The device reports a minimal 64kB page size but it is too late to be >> applied. virtio_iommu_set_page_size_mask() fails and this causes >> vfio_listener_region_add() to end up with hw_error(); >> >> To work around this issue, we transiently enable the IOMMU MR on >> machine init to collect the page size requirements and then restore >> the bypass state. >> >> Fixes: 90519b9053 ("virtio-iommu: Add bypass mode support to assigned >> device") >> Signed-off-by: Eric Auger >> --- >> include/hw/virtio/virtio-iommu.h | 2 ++ >> hw/virtio/virtio-iommu.c | 30 ++++++++++++++++++++++++++++-- >> hw/virtio/trace-events | 1 + >> 3 files changed, 31 insertions(+), 2 deletions(-) >> >> diff --git a/include/hw/virtio/virtio-iommu.h b/include/hw/virtio/virtio- >> iommu.h >> index 2ad5ee320b..a93fc5383e 100644 >> --- a/include/hw/virtio/virtio-iommu.h >> +++ b/include/hw/virtio/virtio-iommu.h >> @@ -61,6 +61,8 @@ struct VirtIOIOMMU { >> QemuRecMutex mutex; >> GTree *endpoints; >> bool boot_bypass; >> + Notifier machine_done; >> + bool granule_frozen; >> }; >> >> #endif >> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c >> index 1cd258135d..1eaf81bab5 100644 >> --- a/hw/virtio/virtio-iommu.c >> +++ b/hw/virtio/virtio-iommu.c >> @@ -24,6 +24,7 @@ >> #include "hw/virtio/virtio.h" >> #include "sysemu/kvm.h" >> #include "sysemu/reset.h" >> +#include "sysemu/sysemu.h" >> #include "qapi/error.h" >> #include "qemu/error-report.h" >> #include "trace.h" >> @@ -1106,12 +1107,12 @@ static int >> virtio_iommu_set_page_size_mask(IOMMUMemoryRegion *mr, >> } >> >> /* >> - * After the machine is finalized, we can't change the mask anymore. If by >> + * Once the granule is frozen we can't change the mask anymore. If by >> * chance the hotplugged device supports the same granule, we can still >> * accept it. Having a different masks is possible but the guest will use >> * sub-optimal block sizes, so warn about it. >> */ >> - if (phase_check(PHASE_MACHINE_READY)) { >> + if (s->granule_frozen) { >> int new_granule = ctz64(new_mask); >> int cur_granule = ctz64(cur_mask); >> >> @@ -1146,6 +1147,27 @@ static void virtio_iommu_system_reset(void >> *opaque) >> >> } >> >> +static void virtio_iommu_freeze_granule(Notifier *notifier, void *data) >> +{ >> + VirtIOIOMMU *s = container_of(notifier, VirtIOIOMMU, machine_done); >> + bool boot_bypass = s->config.bypass; >> + int granule; >> + >> + /* >> + * Transient IOMMU MR enable to collect page_size_mask requirement >> + * through memory_region_iommu_set_page_size_mask() called by >> + * VFIO region_add() callback >> + */ >> + s->config.bypass = 0; >> + virtio_iommu_switch_address_space_all(s); >> + /* restore default */ >> + s->config.bypass = boot_bypass; >> + virtio_iommu_switch_address_space_all(s); >> + s->granule_frozen = true; >> + granule = ctz64(s->config.page_size_mask); >> + trace_virtio_iommu_freeze_granule(BIT(granule)); >> +} > It looks a bit heavy here just in order to get page_size_mask from host side. > But maybe this is the only way with current interface. the problem comes from the fact the regions are aliased due to the bypass and vfio_listener_region_add() does not get a chance to be called until the actual domain attach. So I do not see any other way to transiently enable the region. At least I could check if boot bypass is set before doing that dance. I will respin with that. Thanks Eric > > Thanks > Zhenzhong > >> + >> static void virtio_iommu_device_realize(DeviceState *dev, Error **errp) >> { >> VirtIODevice *vdev = VIRTIO_DEVICE(dev); >> @@ -1189,6 +1211,9 @@ static void virtio_iommu_device_realize(DeviceState >> *dev, Error **errp) >> error_setg(errp, "VIRTIO-IOMMU is not attached to any PCI bus!"); >> } >> >> + s->machine_done.notify = virtio_iommu_freeze_granule; >> + qemu_add_machine_init_done_notifier(&s->machine_done); >> + >> qemu_register_reset(virtio_iommu_system_reset, s); >> } >> >> @@ -1198,6 +1223,7 @@ static void >> virtio_iommu_device_unrealize(DeviceState *dev) >> VirtIOIOMMU *s = VIRTIO_IOMMU(dev); >> >> qemu_unregister_reset(virtio_iommu_system_reset, s); >> + qemu_remove_machine_init_done_notifier(&s->machine_done); >> >> g_hash_table_destroy(s->as_by_busptr); >> if (s->domains) { >> diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events >> index 8f8d05cf9b..68b752e304 100644 >> --- a/hw/virtio/trace-events >> +++ b/hw/virtio/trace-events >> @@ -131,6 +131,7 @@ virtio_iommu_set_page_size_mask(const char *name, >> uint64_t old, uint64_t new) "m >> virtio_iommu_notify_flag_add(const char *name) "add notifier to mr %s" >> virtio_iommu_notify_flag_del(const char *name) "del notifier from mr %s" >> virtio_iommu_switch_address_space(uint8_t bus, uint8_t slot, uint8_t fn, >> bool on) "Device %02x:%02x.%x switching address space (iommu >> enabled=%d)" >> +virtio_iommu_freeze_granule(uint64_t page_size_mask) "granule set to >> 0x%"PRIx64 >> >> # virtio-mem.c >> virtio_mem_send_response(uint16_t type) "type=%" PRIu16 >> -- >> 2.38.1