From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60646) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aiYIJ-0004XB-1c for qemu-devel@nongnu.org; Tue, 22 Mar 2016 22:13:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aiYIF-0003m4-LE for qemu-devel@nongnu.org; Tue, 22 Mar 2016 22:13:10 -0400 Received: from mail-pf0-x244.google.com ([2607:f8b0:400e:c00::244]:35836) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aiYIF-0003hb-9k for qemu-devel@nongnu.org; Tue, 22 Mar 2016 22:13:07 -0400 Received: by mail-pf0-x244.google.com with SMTP id u190so358327pfb.2 for ; Tue, 22 Mar 2016 19:13:05 -0700 (PDT) References: <1458546426-26222-1-git-send-email-aik@ozlabs.ru> <1458546426-26222-18-git-send-email-aik@ozlabs.ru> <20160322051449.GG23586@voom.redhat.com> <56F0DDFF.7050308@ozlabs.ru> <20160323010844.GO23586@voom.redhat.com> From: Alexey Kardashevskiy Message-ID: <56F1FBAB.6090308@ozlabs.ru> Date: Wed, 23 Mar 2016 13:12:59 +1100 MIME-Version: 1.0 In-Reply-To: <20160323010844.GO23586@voom.redhat.com> Content-Type: text/plain; charset=koi8-r; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH qemu v14 17/18] vfio/spapr: Use VFIO_SPAPR_TCE_v2_IOMMU List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson Cc: Alex Williamson , qemu-ppc@nongnu.org, qemu-devel@nongnu.org On 03/23/2016 12:08 PM, David Gibson wrote: > On Tue, Mar 22, 2016 at 04:54:07PM +1100, Alexey Kardashevskiy wrote: >> On 03/22/2016 04:14 PM, David Gibson wrote: >>> On Mon, Mar 21, 2016 at 06:47:05PM +1100, Alexey Kardashevskiy wrote: >>>> New VFIO_SPAPR_TCE_v2_IOMMU type supports dynamic DMA window management. >>>> This adds ability to VFIO common code to dynamically allocate/remove >>>> DMA windows in the host kernel when new VFIO container is added/removed. >>>> >>>> This adds VFIO_IOMMU_SPAPR_TCE_CREATE ioctl to vfio_listener_region_add >>>> and adds just created IOMMU into the host IOMMU list; the opposite >>>> action is taken in vfio_listener_region_del. >>>> >>>> When creating a new window, this uses euristic to decide on the TCE table >>>> levels number. >>>> >>>> This should cause no guest visible change in behavior. >>>> >>>> Signed-off-by: Alexey Kardashevskiy >>>> --- >>>> Changes: >>>> v14: >>>> * new to the series >>>> >>>> --- >>>> TODO: >>>> * export levels to PHB >>>> --- >>>> hw/vfio/common.c | 108 ++++++++++++++++++++++++++++++++++++++++++++++++++++--- >>>> trace-events | 2 ++ >>>> 2 files changed, 105 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c >>>> index 4e873b7..421d6eb 100644 >>>> --- a/hw/vfio/common.c >>>> +++ b/hw/vfio/common.c >>>> @@ -279,6 +279,14 @@ static int vfio_host_iommu_add(VFIOContainer *container, >>>> return 0; >>>> } >>>> >>>> +static void vfio_host_iommu_del(VFIOContainer *container, hwaddr min_iova) >>>> +{ >>>> + VFIOHostIOMMU *hiommu = vfio_host_iommu_lookup(container, min_iova, 0x1000); >>> >>> The hard-coded 0x1000 looks dubious.. >> >> Well, that's the minimal page size... > > Really? Some BookE CPUs support 1KiB page size.. Hm. For IOMMU? Ok. s/0x1000/1/ should do then :) > >>>> + g_assert(hiommu); >>>> + QLIST_REMOVE(hiommu, hiommu_next); >>>> +} >>>> + >>>> static bool vfio_listener_skipped_section(MemoryRegionSection *section) >>>> { >>>> return (!memory_region_is_ram(section->mr) && >>>> @@ -392,6 +400,61 @@ static void vfio_listener_region_add(MemoryListener *listener, >>>> } >>>> end = int128_get64(llend); >>>> >>>> + if (container->iommu_type == VFIO_SPAPR_TCE_v2_IOMMU) { >>> >>> I think this would be clearer split out into a helper function, >>> vfio_create_host_window() or something. >> >> >> It is rather vfio_spapr_create_host_window() and we were avoiding >> xxx_spapr_xxx so far. I'd cut-n-paste the SPAPR PCI AS listener to a >> separate file but this usually triggers more discussion and never ends well. >> >> >> >>>> + unsigned entries, pages; >>>> + struct vfio_iommu_spapr_tce_create create = { .argsz = sizeof(create) }; >>>> + >>>> + g_assert(section->mr->iommu_ops); >>>> + g_assert(memory_region_is_iommu(section->mr)); >>> >>> I don't think you need these asserts. AFAICT the same logic should >>> work if a RAM MR was added directly to PCI address space - this would >>> create the new host window, then the existing code for adding a RAM MR >>> would map that block of RAM statically into the new window. >> >> In what configuration/machine can we do that on SPAPR? > > spapr guests won't ever do that. But you can run an x86 guest on a > powernv host and this situation could come up. I am pretty sure VFIO won't work in this case anyway. > In any case there's no point asserting if the code is correct anyway. Assert here says (at least) "not tested" or "not expected to happen". > >>>> + trace_vfio_listener_region_add_iommu(iova, end - 1); >>>> + /* >>>> + * FIXME: For VFIO iommu types which have KVM acceleration to >>>> + * avoid bouncing all map/unmaps through qemu this way, this >>>> + * would be the right place to wire that up (tell the KVM >>>> + * device emulation the VFIO iommu handles to use). >>>> + */ >>>> + create.window_size = memory_region_size(section->mr); >>>> + create.page_shift = >>>> + ctz64(section->mr->iommu_ops->get_page_sizes(section->mr)); >>> >>> Ah.. except that I guess you'd need to fall back to host page size >>> here to handle a RAM MR. >> >> Can you give an example of such RAM MR being added to PCI AS on >> SPAPR? > > On spapr, no. But you can run other machine types as guests (at least > with TCG) on a host with the spapr IOMMU. > >>>> + /* >>>> + * SPAPR host supports multilevel TCE tables, there is some >>>> + * euristic to decide how many levels we want for our table: >>>> + * 0..64 = 1; 65..4096 = 2; 4097..262144 = 3; 262145.. = 4 >>>> + */ >>>> + entries = create.window_size >> create.page_shift; >>>> + pages = (entries * sizeof(uint64_t)) / getpagesize(); >>>> + create.levels = ctz64(pow2ceil(pages) - 1) / 6 + 1; >>>> + >>>> + ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_CREATE, &create); >>>> + if (ret) { >>>> + error_report("Failed to create a window, ret = %d (%m)", ret); >>>> + goto fail; >>>> + } >>>> + >>>> + if (create.start_addr != section->offset_within_address_space || >>>> + vfio_host_iommu_lookup(container, create.start_addr, >>>> + create.start_addr + create.window_size - 1)) { >>> >>> Under what circumstances can this trigger? Is the kernel ioctl >>> allowed to return a different window start address than the one >>> requested? >> >> You already asked this some time ago :) The userspace cannot request >> address, the host kernel returns one. > > Ok. For generality it would be nice if you could succeed here as long > as the new host window covers the requested guest window, even if it > doesn't match exactly. And for that matter to not request the new > window if the host already has a window covering the guest region. That would be dead code - when would it possibly work? I mean I could instrument an artificial test but the actual user which might appear later will likely be soooo different so this won't help anyway. >>> The second check looks very strange - if it returns true doesn't that >>> mean you *do* have host window which can accomodate this guest region, >>> which is what you want? >> >> This should not happen, this is what this check is for. Can make it assert() >> or something like this. > > Oh.. I see. Because you've done the ioctl, but not recorded the new > host window in the list yet. > > No, I think the correct approach is to look for an existing host > window containing the requested guest window *before* you try to > create a new host window. If one is already there, you can just carry > on. Right, I'll change this. > >>>> + struct vfio_iommu_spapr_tce_remove remove = { >>>> + .argsz = sizeof(remove), >>>> + .start_addr = create.start_addr >>>> + }; >>>> + error_report("Host doesn't support DMA window at %"HWADDR_PRIx", must be %"PRIx64, >>>> + section->offset_within_address_space, >>>> + create.start_addr); >>>> + ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_REMOVE, &remove); >>>> + ret = -EINVAL; >>>> + goto fail; >>>> + } >>>> + trace_vfio_spapr_create_window(create.page_shift, >>>> + create.window_size, >>>> + create.start_addr); >>>> + >>>> + vfio_host_iommu_add(container, create.start_addr, >>>> + create.start_addr + create.window_size - 1, >>>> + 1ULL << create.page_shift); >>>> + } >>>> + >>>> if (!vfio_host_iommu_lookup(container, iova, end - 1)) { >>>> error_report("vfio: IOMMU container %p can't map guest IOVA region" >>>> " 0x%"HWADDR_PRIx"..0x%"HWADDR_PRIx, >>>> @@ -525,6 +588,22 @@ static void vfio_listener_region_del(MemoryListener *listener, >>>> container, iova, end - iova, ret); >>>> } >>>> >>>> + if (container->iommu_type == VFIO_SPAPR_TCE_v2_IOMMU) { >>>> + struct vfio_iommu_spapr_tce_remove remove = { >>>> + .argsz = sizeof(remove), >>>> + .start_addr = section->offset_within_address_space, >>>> + }; >>>> + ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_REMOVE, &remove); >>>> + if (ret) { >>>> + error_report("Failed to remove window at %"PRIx64, >>>> + remove.start_addr); >>>> + } >>>> + >>>> + vfio_host_iommu_del(container, section->offset_within_address_space); >>>> + >>>> + trace_vfio_spapr_remove_window(remove.start_addr); >>>> + } >>>> + >>>> if (iommu && iommu->iommu_ops && iommu->iommu_ops->vfio_stop) { >>>> iommu->iommu_ops->vfio_stop(section->mr); >>>> } >>>> @@ -928,11 +1007,30 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as) >>>> goto listener_release_exit; >>>> } >>>> >>>> - /* The default table uses 4K pages */ >>>> - vfio_host_iommu_add(container, info.dma32_window_start, >>>> - info.dma32_window_start + >>>> - info.dma32_window_size - 1, >>>> - 0x1000); >>>> + if (v2) { >>>> + /* >>>> + * There is a default window in just created container. >>>> + * To make region_add/del simpler, we better remove this >>>> + * window now and let those iommu_listener callbacks >>>> + * create/remove them when needed. >>>> + */ >>>> + struct vfio_iommu_spapr_tce_remove remove = { >>>> + .argsz = sizeof(remove), >>>> + .start_addr = info.dma32_window_start, >>>> + }; >>>> + ret = ioctl(fd, VFIO_IOMMU_SPAPR_TCE_REMOVE, &remove); >>>> + if (ret) { >>>> + error_report("vfio: VFIO_IOMMU_SPAPR_TCE_REMOVE failed: %m"); >>>> + ret = -errno; >>>> + goto free_container_exit; >>>> + } >>>> + } else { >>>> + /* The default table uses 4K pages */ >>>> + vfio_host_iommu_add(container, info.dma32_window_start, >>>> + info.dma32_window_start + >>>> + info.dma32_window_size - 1, >>>> + 0x1000); >>>> + } >>>> } else { >>>> error_report("vfio: No available IOMMU models"); >>>> ret = -EINVAL; >>>> diff --git a/trace-events b/trace-events >>>> index cc619e1..f2b75a3 100644 >>>> --- a/trace-events >>>> +++ b/trace-events >>>> @@ -1736,6 +1736,8 @@ vfio_region_finalize(const char *name, int index) "Device %s, region %d" >>>> vfio_region_mmaps_set_enabled(const char *name, bool enabled) "Region %s mmaps enabled: %d" >>>> vfio_ram_register(uint64_t va, uint64_t size, int ret) "va=%"PRIx64" size=%"PRIx64" ret=%d" >>>> vfio_ram_unregister(uint64_t va, uint64_t size, int ret) "va=%"PRIx64" size=%"PRIx64" ret=%d" >>>> +vfio_spapr_create_window(int ps, uint64_t ws, uint64_t off) "pageshift=0x%x winsize=0x%"PRIx64" offset=0x%"PRIx64 >>>> +vfio_spapr_remove_window(uint64_t off) "offset=%"PRIx64 >>>> >>>> # hw/vfio/platform.c >>>> vfio_platform_base_device_init(char *name, int groupid) "%s belongs to group #%d" >>> >> >> > -- Alexey