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pr=C From: Stewart Hildebrand To: CC: Oleksandr Andrushchenko , Jan Beulich , Andrew Cooper , =?utf-8?q?Roger_Pau_Monn=C3=A9?= , Wei Liu , George Dunlap , Julien Grall , Stefano Stabellini , Jun Nakajima , Kevin Tian , Paul Durrant , Volodymyr Babchuk , "Stewart Hildebrand" Subject: [PATCH v12 01/15] vpci: use per-domain PCI lock to protect vpci structure Date: Tue, 9 Jan 2024 16:51:16 -0500 Message-ID: <20240109215145.430207-2-stewart.hildebrand@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240109215145.430207-1-stewart.hildebrand@amd.com> References: <20240109215145.430207-1-stewart.hildebrand@amd.com> MIME-Version: 1.0 X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL6PEPF0001AB4B:EE_|CH2PR12MB4859:EE_ X-MS-Office365-Filtering-Correlation-Id: b3085e0f-5073-4dd2-11b4-08dc115d39e6 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230031)(4636009)(136003)(39860400002)(346002)(396003)(376002)(230922051799003)(1800799012)(82310400011)(186009)(451199024)(64100799003)(46966006)(40470700004)(36840700001)(30864003)(7416002)(41300700001)(81166007)(2906002)(5660300002)(82740400003)(54906003)(44832011)(40460700003)(36756003)(36860700001)(86362001)(356005)(6916009)(40480700001)(6666004)(316002)(8676002)(8936002)(4326008)(70586007)(70206006)(47076005)(83380400001)(336012)(1076003)(26005)(478600001)(426003)(2616005)(36900700001)(309714004);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Jan 2024 21:52:08.0308 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: b3085e0f-5073-4dd2-11b4-08dc115d39e6 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BL6PEPF0001AB4B.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH2PR12MB4859 From: Oleksandr Andrushchenko Use a previously introduced per-domain read/write lock to check whether vpci is present, so we are sure there are no accesses to the contents of the vpci struct if not. This lock can be used (and in a few cases is used right away) so that vpci removal can be performed while holding the lock in write mode. Previously such removal could race with vpci_read for example. When taking both d->pci_lock and pdev->vpci->lock, they should be taken in this exact order: d->pci_lock then pdev->vpci->lock to avoid possible deadlock situations. 1. Per-domain's pci_lock is used to protect pdev->vpci structure from being removed. 2. Writing the command register and ROM BAR register may trigger modify_bars to run, which in turn may access multiple pdevs while checking for the existing BAR's overlap. The overlapping check, if done under the read lock, requires vpci->lock to be acquired on both devices being compared, which may produce a deadlock. It is not possible to upgrade read lock to write lock in such a case. So, in order to prevent the deadlock, use d->pci_lock instead. All other code, which doesn't lead to pdev->vpci destruction and does not access multiple pdevs at the same time, can still use a combination of the read lock and pdev->vpci->lock. 3. Drop const qualifier where the new rwlock is used and this is appropriate. 4. Do not call process_pending_softirqs with any locks held. For that unlock prior the call and re-acquire the locks after. After re-acquiring the lock there is no need to check if pdev->vpci exists: - in apply_map because of the context it is called (no race condition possible) - for MSI/MSI-X debug code because it is called at the end of pdev->vpci access and no further access to pdev->vpci is made 5. Use d->pci_lock around for_each_pdev and pci_get_pdev_by_domain while accessing pdevs in vpci code. Suggested-by: Roger Pau Monné Suggested-by: Jan Beulich Signed-off-by: Oleksandr Andrushchenko Signed-off-by: Volodymyr Babchuk Signed-off-by: Stewart Hildebrand Reviewed-by: Roger Pau Monné --- Changes in v12: - s/pci_rwlock/pci_lock/ in commit message - expand comment about scope of pci_lock in sched.h - in vpci_{read,write}, if hwdom is trying to access a device assigned to dom_xen, holding hwdom->pci_lock is sufficient (no need to hold dom_xen->pci_lock) - reintroduce ASSERT in vmx_pi_update_irte() - reintroduce ASSERT in __pci_enable_msi{x}() - delete note 6. in commit message about removing ASSERTs since we have reintroduced them Changes in v11: - Fixed commit message regarding possible spinlocks - Removed parameter from allocate_and_map_msi_pirq(), which was added in the prev version. Now we are taking pcidevs_lock in physdev_map_pirq() - Returned ASSERT to pci_enable_msi - Fixed case when we took read lock instead of write one - Fixed label indentation Changes in v10: - Moved printk pas locked area - Returned back ASSERTs - Added new parameter to allocate_and_map_msi_pirq() so it knows if it should take the global pci lock - Added comment about possible improvement in vpci_write - Changed ASSERT(rw_is_locked()) to rw_is_write_locked() in appropriate places - Renamed release_domain_locks() to release_domain_write_locks() - moved domain_done label in vpci_dump_msi() to correct place Changes in v9: - extended locked region to protect vpci_remove_device and vpci_add_handlers() calls - vpci_write() takes lock in the write mode to protect potential call to modify_bars() - renamed lock releasing function - removed ASSERT()s from msi code - added trylock in vpci_dump_msi Changes in v8: - changed d->vpci_lock to d->pci_lock - introducing d->pci_lock in a separate patch - extended locked region in vpci_process_pending - removed pcidevs_lockis vpci_dump_msi() - removed some changes as they are not needed with the new locking scheme - added handling for hwdom && dom_xen case --- xen/arch/x86/hvm/vmsi.c | 22 +++++++-------- xen/arch/x86/hvm/vmx/vmx.c | 2 +- xen/arch/x86/irq.c | 8 +++--- xen/arch/x86/msi.c | 14 +++++----- xen/arch/x86/physdev.c | 2 ++ xen/drivers/passthrough/pci.c | 9 +++--- xen/drivers/vpci/header.c | 18 ++++++++++++ xen/drivers/vpci/msi.c | 28 +++++++++++++++++-- xen/drivers/vpci/msix.c | 52 ++++++++++++++++++++++++++++++----- xen/drivers/vpci/vpci.c | 28 ++++++++++++++++--- xen/include/xen/sched.h | 3 +- 11 files changed, 144 insertions(+), 42 deletions(-) diff --git a/xen/arch/x86/hvm/vmsi.c b/xen/arch/x86/hvm/vmsi.c index 128f23636279..03caf91beefc 100644 --- a/xen/arch/x86/hvm/vmsi.c +++ b/xen/arch/x86/hvm/vmsi.c @@ -468,7 +468,7 @@ int msixtbl_pt_register(struct domain *d, struct pirq *pirq, uint64_t gtable) struct msixtbl_entry *entry, *new_entry; int r = -EINVAL; - ASSERT(pcidevs_locked()); + ASSERT(pcidevs_locked() || rw_is_locked(&d->pci_lock)); ASSERT(rw_is_write_locked(&d->event_lock)); if ( !msixtbl_initialised(d) ) @@ -538,7 +538,7 @@ void msixtbl_pt_unregister(struct domain *d, struct pirq *pirq) struct pci_dev *pdev; struct msixtbl_entry *entry; - ASSERT(pcidevs_locked()); + ASSERT(pcidevs_locked() || rw_is_locked(&d->pci_lock)); ASSERT(rw_is_write_locked(&d->event_lock)); if ( !msixtbl_initialised(d) ) @@ -684,7 +684,7 @@ static int vpci_msi_update(const struct pci_dev *pdev, uint32_t data, { unsigned int i; - ASSERT(pcidevs_locked()); + ASSERT(rw_is_locked(&pdev->domain->pci_lock)); if ( (address & MSI_ADDR_BASE_MASK) != MSI_ADDR_HEADER ) { @@ -725,8 +725,8 @@ void vpci_msi_arch_update(struct vpci_msi *msi, const struct pci_dev *pdev) int rc; ASSERT(msi->arch.pirq != INVALID_PIRQ); + ASSERT(rw_is_locked(&pdev->domain->pci_lock)); - pcidevs_lock(); for ( i = 0; i < msi->vectors && msi->arch.bound; i++ ) { struct xen_domctl_bind_pt_irq unbind = { @@ -745,7 +745,6 @@ void vpci_msi_arch_update(struct vpci_msi *msi, const struct pci_dev *pdev) msi->arch.bound = !vpci_msi_update(pdev, msi->data, msi->address, msi->vectors, msi->arch.pirq, msi->mask); - pcidevs_unlock(); } static int vpci_msi_enable(const struct pci_dev *pdev, unsigned int nr, @@ -778,15 +777,14 @@ int vpci_msi_arch_enable(struct vpci_msi *msi, const struct pci_dev *pdev, int rc; ASSERT(msi->arch.pirq == INVALID_PIRQ); + ASSERT(rw_is_locked(&pdev->domain->pci_lock)); rc = vpci_msi_enable(pdev, vectors, 0); if ( rc < 0 ) return rc; msi->arch.pirq = rc; - pcidevs_lock(); msi->arch.bound = !vpci_msi_update(pdev, msi->data, msi->address, vectors, msi->arch.pirq, msi->mask); - pcidevs_unlock(); return 0; } @@ -797,8 +795,8 @@ static void vpci_msi_disable(const struct pci_dev *pdev, int pirq, unsigned int i; ASSERT(pirq != INVALID_PIRQ); + ASSERT(rw_is_locked(&pdev->domain->pci_lock)); - pcidevs_lock(); for ( i = 0; i < nr && bound; i++ ) { struct xen_domctl_bind_pt_irq bind = { @@ -814,7 +812,6 @@ static void vpci_msi_disable(const struct pci_dev *pdev, int pirq, write_lock(&pdev->domain->event_lock); unmap_domain_pirq(pdev->domain, pirq); write_unlock(&pdev->domain->event_lock); - pcidevs_unlock(); } void vpci_msi_arch_disable(struct vpci_msi *msi, const struct pci_dev *pdev) @@ -854,6 +851,7 @@ int vpci_msix_arch_enable_entry(struct vpci_msix_entry *entry, int rc; ASSERT(entry->arch.pirq == INVALID_PIRQ); + ASSERT(rw_is_locked(&pdev->domain->pci_lock)); rc = vpci_msi_enable(pdev, vmsix_entry_nr(pdev->vpci->msix, entry), table_base); if ( rc < 0 ) @@ -861,7 +859,6 @@ int vpci_msix_arch_enable_entry(struct vpci_msix_entry *entry, entry->arch.pirq = rc; - pcidevs_lock(); rc = vpci_msi_update(pdev, entry->data, entry->addr, 1, entry->arch.pirq, entry->masked); if ( rc ) @@ -869,7 +866,6 @@ int vpci_msix_arch_enable_entry(struct vpci_msix_entry *entry, vpci_msi_disable(pdev, entry->arch.pirq, 1, false); entry->arch.pirq = INVALID_PIRQ; } - pcidevs_unlock(); return rc; } @@ -895,6 +891,8 @@ int vpci_msix_arch_print(const struct vpci_msix *msix) { unsigned int i; + ASSERT(rw_is_locked(&msix->pdev->domain->pci_lock)); + for ( i = 0; i < msix->max_entries; i++ ) { const struct vpci_msix_entry *entry = &msix->entries[i]; @@ -913,7 +911,9 @@ int vpci_msix_arch_print(const struct vpci_msix *msix) struct pci_dev *pdev = msix->pdev; spin_unlock(&msix->pdev->vpci->lock); + read_unlock(&pdev->domain->pci_lock); process_pending_softirqs(); + read_lock(&pdev->domain->pci_lock); /* NB: we assume that pdev cannot go away for an alive domain. */ if ( !pdev->vpci || !spin_trylock(&pdev->vpci->lock) ) return -EBUSY; diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index 8ff675883c2b..890faef48b82 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -413,7 +413,7 @@ static int cf_check vmx_pi_update_irte(const struct vcpu *v, spin_unlock_irq(&desc->lock); - ASSERT(pcidevs_locked()); + ASSERT(pcidevs_locked() || rw_is_locked(&msi_desc->dev->domain->pci_lock)); return iommu_update_ire_from_msi(msi_desc, &msi_desc->msg); diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c index 50e49e1a4b6f..4d89d9af99fe 100644 --- a/xen/arch/x86/irq.c +++ b/xen/arch/x86/irq.c @@ -2166,7 +2166,7 @@ int map_domain_pirq( struct pci_dev *pdev; unsigned int nr = 0; - ASSERT(pcidevs_locked()); + ASSERT(pcidevs_locked() || rw_is_locked(&d->pci_lock)); ret = -ENODEV; if ( !cpu_has_apic ) @@ -2323,7 +2323,7 @@ int unmap_domain_pirq(struct domain *d, int pirq) if ( (pirq < 0) || (pirq >= d->nr_pirqs) ) return -EINVAL; - ASSERT(pcidevs_locked()); + ASSERT(pcidevs_locked() || rw_is_locked(&d->pci_lock)); ASSERT(rw_is_write_locked(&d->event_lock)); info = pirq_info(d, pirq); @@ -2888,6 +2888,8 @@ int allocate_and_map_msi_pirq(struct domain *d, int index, int *pirq_p, { int irq, pirq, ret; + ASSERT(pcidevs_locked() || rw_is_locked(&d->pci_lock)); + switch ( type ) { case MAP_PIRQ_TYPE_MSI: @@ -2917,7 +2919,6 @@ int allocate_and_map_msi_pirq(struct domain *d, int index, int *pirq_p, msi->irq = irq; - pcidevs_lock(); /* Verify or get pirq. */ write_lock(&d->event_lock); pirq = allocate_pirq(d, index, *pirq_p, irq, type, &msi->entry_nr); @@ -2933,7 +2934,6 @@ int allocate_and_map_msi_pirq(struct domain *d, int index, int *pirq_p, done: write_unlock(&d->event_lock); - pcidevs_unlock(); if ( ret ) { switch ( type ) diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c index 335c0868a225..7da2affa2e82 100644 --- a/xen/arch/x86/msi.c +++ b/xen/arch/x86/msi.c @@ -602,7 +602,7 @@ static int msi_capability_init(struct pci_dev *dev, unsigned int i, mpos; uint16_t control; - ASSERT(pcidevs_locked()); + ASSERT(pcidevs_locked() || rw_is_locked(&dev->domain->pci_lock)); pos = pci_find_cap_offset(dev->sbdf, PCI_CAP_ID_MSI); if ( !pos ) return -ENODEV; @@ -771,7 +771,7 @@ static int msix_capability_init(struct pci_dev *dev, if ( !pos ) return -ENODEV; - ASSERT(pcidevs_locked()); + ASSERT(pcidevs_locked() || rw_is_locked(&dev->domain->pci_lock)); control = pci_conf_read16(dev->sbdf, msix_control_reg(pos)); /* @@ -988,11 +988,11 @@ static int __pci_enable_msi(struct pci_dev *pdev, struct msi_info *msi, { struct msi_desc *old_desc; - ASSERT(pcidevs_locked()); - if ( !pdev ) return -ENODEV; + ASSERT(pcidevs_locked() || rw_is_locked(&pdev->domain->pci_lock)); + old_desc = find_msi_entry(pdev, msi->irq, PCI_CAP_ID_MSI); if ( old_desc ) { @@ -1043,11 +1043,11 @@ static int __pci_enable_msix(struct pci_dev *pdev, struct msi_info *msi, { struct msi_desc *old_desc; - ASSERT(pcidevs_locked()); - if ( !pdev || !pdev->msix ) return -ENODEV; + ASSERT(pcidevs_locked() || rw_is_locked(&pdev->domain->pci_lock)); + if ( msi->entry_nr >= pdev->msix->nr_entries ) return -EINVAL; @@ -1154,7 +1154,7 @@ int pci_prepare_msix(u16 seg, u8 bus, u8 devfn, bool off) int pci_enable_msi(struct pci_dev *pdev, struct msi_info *msi, struct msi_desc **desc) { - ASSERT(pcidevs_locked()); + ASSERT(pcidevs_locked() || rw_is_locked(&pdev->domain->pci_lock)); if ( !use_msi ) return -EPERM; diff --git a/xen/arch/x86/physdev.c b/xen/arch/x86/physdev.c index 47c4da0af7e1..369c9e788c1c 100644 --- a/xen/arch/x86/physdev.c +++ b/xen/arch/x86/physdev.c @@ -123,7 +123,9 @@ int physdev_map_pirq(domid_t domid, int type, int *index, int *pirq_p, case MAP_PIRQ_TYPE_MSI: case MAP_PIRQ_TYPE_MULTI_MSI: + pcidevs_lock(); ret = allocate_and_map_msi_pirq(d, *index, pirq_p, type, msi); + pcidevs_unlock(); break; default: diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c index 1439d1ef2b26..3a973324bca1 100644 --- a/xen/drivers/passthrough/pci.c +++ b/xen/drivers/passthrough/pci.c @@ -750,7 +750,6 @@ int pci_add_device(u16 seg, u8 bus, u8 devfn, pdev->domain = hardware_domain; write_lock(&hardware_domain->pci_lock); list_add(&pdev->domain_list, &hardware_domain->pdev_list); - write_unlock(&hardware_domain->pci_lock); /* * For devices not discovered by Xen during boot, add vPCI handlers @@ -759,18 +758,18 @@ int pci_add_device(u16 seg, u8 bus, u8 devfn, ret = vpci_add_handlers(pdev); if ( ret ) { - printk(XENLOG_ERR "Setup of vPCI failed: %d\n", ret); - write_lock(&hardware_domain->pci_lock); list_del(&pdev->domain_list); write_unlock(&hardware_domain->pci_lock); pdev->domain = NULL; + printk(XENLOG_ERR "Setup of vPCI failed: %d\n", ret); goto out; } + write_unlock(&hardware_domain->pci_lock); ret = iommu_add_device(pdev); if ( ret ) { - vpci_remove_device(pdev); write_lock(&hardware_domain->pci_lock); + vpci_remove_device(pdev); list_del(&pdev->domain_list); write_unlock(&hardware_domain->pci_lock); pdev->domain = NULL; @@ -1146,7 +1145,9 @@ static void __hwdom_init setup_one_hwdom_device(const struct setup_hwdom *ctxt, } while ( devfn != pdev->devfn && PCI_SLOT(devfn) == PCI_SLOT(pdev->devfn) ); + write_lock(&ctxt->d->pci_lock); err = vpci_add_handlers(pdev); + write_unlock(&ctxt->d->pci_lock); if ( err ) printk(XENLOG_ERR "setup of vPCI for d%d failed: %d\n", ctxt->d->domain_id, err); diff --git a/xen/drivers/vpci/header.c b/xen/drivers/vpci/header.c index 58195549d50a..8f5850b8cf6d 100644 --- a/xen/drivers/vpci/header.c +++ b/xen/drivers/vpci/header.c @@ -173,6 +173,7 @@ bool vpci_process_pending(struct vcpu *v) if ( rc == -ERESTART ) return true; + write_lock(&v->domain->pci_lock); spin_lock(&v->vpci.pdev->vpci->lock); /* Disable memory decoding unconditionally on failure. */ modify_decoding(v->vpci.pdev, @@ -191,6 +192,7 @@ bool vpci_process_pending(struct vcpu *v) * failure. */ vpci_remove_device(v->vpci.pdev); + write_unlock(&v->domain->pci_lock); } return false; @@ -202,8 +204,20 @@ static int __init apply_map(struct domain *d, const struct pci_dev *pdev, struct map_data data = { .d = d, .map = true }; int rc; + ASSERT(rw_is_write_locked(&d->pci_lock)); + while ( (rc = rangeset_consume_ranges(mem, map_range, &data)) == -ERESTART ) + { + /* + * It's safe to drop and reacquire the lock in this context + * without risking pdev disappearing because devices cannot be + * removed until the initial domain has been started. + */ + write_unlock(&d->pci_lock); process_pending_softirqs(); + write_lock(&d->pci_lock); + } + rangeset_destroy(mem); if ( !rc ) modify_decoding(pdev, cmd, false); @@ -244,6 +258,8 @@ static int modify_bars(const struct pci_dev *pdev, uint16_t cmd, bool rom_only) unsigned int i; int rc; + ASSERT(rw_is_write_locked(&pdev->domain->pci_lock)); + if ( !mem ) return -ENOMEM; @@ -524,6 +540,8 @@ static int cf_check init_header(struct pci_dev *pdev) int rc; bool mask_cap_list = false; + ASSERT(rw_is_write_locked(&pdev->domain->pci_lock)); + switch ( pci_conf_read8(pdev->sbdf, PCI_HEADER_TYPE) & 0x7f ) { case PCI_HEADER_TYPE_NORMAL: diff --git a/xen/drivers/vpci/msi.c b/xen/drivers/vpci/msi.c index a253ccbd7db7..6ff71e5f9ab7 100644 --- a/xen/drivers/vpci/msi.c +++ b/xen/drivers/vpci/msi.c @@ -263,7 +263,7 @@ REGISTER_VPCI_INIT(init_msi, VPCI_PRIORITY_LOW); void vpci_dump_msi(void) { - const struct domain *d; + struct domain *d; rcu_read_lock(&domlist_read_lock); for_each_domain ( d ) @@ -275,6 +275,9 @@ void vpci_dump_msi(void) printk("vPCI MSI/MSI-X d%d\n", d->domain_id); + if ( !read_trylock(&d->pci_lock) ) + continue; + for_each_pdev ( d, pdev ) { const struct vpci_msi *msi; @@ -316,14 +319,33 @@ void vpci_dump_msi(void) * holding the lock. */ printk("unable to print all MSI-X entries: %d\n", rc); - process_pending_softirqs(); - continue; + goto pdev_done; } } spin_unlock(&pdev->vpci->lock); + pdev_done: + /* + * Unlock lock to process pending softirqs. This is + * potentially unsafe, as d->pdev_list can be changed in + * meantime. + */ + read_unlock(&d->pci_lock); process_pending_softirqs(); + if ( !read_trylock(&d->pci_lock) ) + { + printk("unable to access other devices for the domain\n"); + goto domain_done; + } } + read_unlock(&d->pci_lock); + domain_done: + /* + * We need this label at the end of the loop, but some + * compilers might not be happy about label at the end of the + * compound statement so we adding an empty statement here. + */ + ; } rcu_read_unlock(&domlist_read_lock); } diff --git a/xen/drivers/vpci/msix.c b/xen/drivers/vpci/msix.c index d1126a417da9..b6abab47efdd 100644 --- a/xen/drivers/vpci/msix.c +++ b/xen/drivers/vpci/msix.c @@ -147,6 +147,8 @@ static struct vpci_msix *msix_find(const struct domain *d, unsigned long addr) { struct vpci_msix *msix; + ASSERT(rw_is_locked(&d->pci_lock)); + list_for_each_entry ( msix, &d->arch.hvm.msix_tables, next ) { const struct vpci_bar *bars = msix->pdev->vpci->header.bars; @@ -163,7 +165,13 @@ static struct vpci_msix *msix_find(const struct domain *d, unsigned long addr) static int cf_check msix_accept(struct vcpu *v, unsigned long addr) { - return !!msix_find(v->domain, addr); + int rc; + + read_lock(&v->domain->pci_lock); + rc = !!msix_find(v->domain, addr); + read_unlock(&v->domain->pci_lock); + + return rc; } static bool access_allowed(const struct pci_dev *pdev, unsigned long addr, @@ -358,21 +366,35 @@ static int adjacent_read(const struct domain *d, const struct vpci_msix *msix, static int cf_check msix_read( struct vcpu *v, unsigned long addr, unsigned int len, unsigned long *data) { - const struct domain *d = v->domain; - struct vpci_msix *msix = msix_find(d, addr); + struct domain *d = v->domain; + struct vpci_msix *msix; const struct vpci_msix_entry *entry; unsigned int offset; *data = ~0UL; + read_lock(&d->pci_lock); + + msix = msix_find(d, addr); if ( !msix ) + { + read_unlock(&d->pci_lock); return X86EMUL_RETRY; + } if ( adjacent_handle(msix, addr) ) - return adjacent_read(d, msix, addr, len, data); + { + int rc = adjacent_read(d, msix, addr, len, data); + + read_unlock(&d->pci_lock); + return rc; + } if ( !access_allowed(msix->pdev, addr, len) ) + { + read_unlock(&d->pci_lock); return X86EMUL_OKAY; + } spin_lock(&msix->pdev->vpci->lock); entry = get_entry(msix, addr); @@ -404,6 +426,7 @@ static int cf_check msix_read( break; } spin_unlock(&msix->pdev->vpci->lock); + read_unlock(&d->pci_lock); return X86EMUL_OKAY; } @@ -491,19 +514,33 @@ static int adjacent_write(const struct domain *d, const struct vpci_msix *msix, static int cf_check msix_write( struct vcpu *v, unsigned long addr, unsigned int len, unsigned long data) { - const struct domain *d = v->domain; - struct vpci_msix *msix = msix_find(d, addr); + struct domain *d = v->domain; + struct vpci_msix *msix; struct vpci_msix_entry *entry; unsigned int offset; + read_lock(&d->pci_lock); + + msix = msix_find(d, addr); if ( !msix ) + { + read_unlock(&d->pci_lock); return X86EMUL_RETRY; + } if ( adjacent_handle(msix, addr) ) - return adjacent_write(d, msix, addr, len, data); + { + int rc = adjacent_write(d, msix, addr, len, data); + + read_unlock(&d->pci_lock); + return rc; + } if ( !access_allowed(msix->pdev, addr, len) ) + { + read_unlock(&d->pci_lock); return X86EMUL_OKAY; + } spin_lock(&msix->pdev->vpci->lock); entry = get_entry(msix, addr); @@ -579,6 +616,7 @@ static int cf_check msix_write( break; } spin_unlock(&msix->pdev->vpci->lock); + read_unlock(&d->pci_lock); return X86EMUL_OKAY; } diff --git a/xen/drivers/vpci/vpci.c b/xen/drivers/vpci/vpci.c index 72ef277c4f8e..a1a004460491 100644 --- a/xen/drivers/vpci/vpci.c +++ b/xen/drivers/vpci/vpci.c @@ -42,6 +42,8 @@ extern vpci_register_init_t *const __end_vpci_array[]; void vpci_remove_device(struct pci_dev *pdev) { + ASSERT(rw_is_write_locked(&pdev->domain->pci_lock)); + if ( !has_vpci(pdev->domain) || !pdev->vpci ) return; @@ -77,6 +79,8 @@ int vpci_add_handlers(struct pci_dev *pdev) const unsigned long *ro_map; int rc = 0; + ASSERT(rw_is_write_locked(&pdev->domain->pci_lock)); + if ( !has_vpci(pdev->domain) ) return 0; @@ -361,7 +365,7 @@ static uint32_t merge_result(uint32_t data, uint32_t new, unsigned int size, uint32_t vpci_read(pci_sbdf_t sbdf, unsigned int reg, unsigned int size) { - const struct domain *d = current->domain; + struct domain *d = current->domain; const struct pci_dev *pdev; const struct vpci_register *r; unsigned int data_offset = 0; @@ -375,13 +379,19 @@ uint32_t vpci_read(pci_sbdf_t sbdf, unsigned int reg, unsigned int size) /* * Find the PCI dev matching the address, which for hwdom also requires - * consulting DomXEN. Passthrough everything that's not trapped. + * consulting DomXEN. Passthrough everything that's not trapped. + * If this is hwdom and the device is assigned to dom_xen, acquiring hwdom's + * pci_lock is sufficient. */ + read_lock(&d->pci_lock); pdev = pci_get_pdev(d, sbdf); if ( !pdev && is_hardware_domain(d) ) pdev = pci_get_pdev(dom_xen, sbdf); if ( !pdev || !pdev->vpci ) + { + read_unlock(&d->pci_lock); return vpci_read_hw(sbdf, reg, size); + } spin_lock(&pdev->vpci->lock); @@ -428,6 +438,7 @@ uint32_t vpci_read(pci_sbdf_t sbdf, unsigned int reg, unsigned int size) ASSERT(data_offset < size); } spin_unlock(&pdev->vpci->lock); + read_unlock(&d->pci_lock); if ( data_offset < size ) { @@ -470,7 +481,7 @@ static void vpci_write_helper(const struct pci_dev *pdev, void vpci_write(pci_sbdf_t sbdf, unsigned int reg, unsigned int size, uint32_t data) { - const struct domain *d = current->domain; + struct domain *d = current->domain; const struct pci_dev *pdev; const struct vpci_register *r; unsigned int data_offset = 0; @@ -483,8 +494,14 @@ void vpci_write(pci_sbdf_t sbdf, unsigned int reg, unsigned int size, /* * Find the PCI dev matching the address, which for hwdom also requires - * consulting DomXEN. Passthrough everything that's not trapped. + * consulting DomXEN. Passthrough everything that's not trapped. + * If this is hwdom and the device is assigned to dom_xen, acquiring hwdom's + * pci_lock is sufficient. + * + * TODO: We need to take pci_locks in exclusive mode only if we + * are modifying BARs, so there is a room for improvement. */ + write_lock(&d->pci_lock); pdev = pci_get_pdev(d, sbdf); if ( !pdev && is_hardware_domain(d) ) pdev = pci_get_pdev(dom_xen, sbdf); @@ -493,6 +510,8 @@ void vpci_write(pci_sbdf_t sbdf, unsigned int reg, unsigned int size, /* Ignore writes to read-only devices, which have no ->vpci. */ const unsigned long *ro_map = pci_get_ro_map(sbdf.seg); + write_unlock(&d->pci_lock); + if ( !ro_map || !test_bit(sbdf.bdf, ro_map) ) vpci_write_hw(sbdf, reg, size, data); return; @@ -534,6 +553,7 @@ void vpci_write(pci_sbdf_t sbdf, unsigned int reg, unsigned int size, ASSERT(data_offset < size); } spin_unlock(&pdev->vpci->lock); + write_unlock(&d->pci_lock); if ( data_offset < size ) /* Tailing gap, write the remaining. */ diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h index 9da91e0e6244..37f5922f3206 100644 --- a/xen/include/xen/sched.h +++ b/xen/include/xen/sched.h @@ -462,7 +462,8 @@ struct domain #ifdef CONFIG_HAS_PCI struct list_head pdev_list; /* - * pci_lock protects access to pdev_list. + * pci_lock protects access to pdev_list. pci_lock also protects pdev->vpci + * structure from being removed. * * Any user *reading* from pdev_list, or from devices stored in pdev_list, * should hold either pcidevs_lock() or pci_lock in read mode. Optionally,