From: Alexey Kardashevskiy aik@ozlabs.ru
[ Upstream commit c37c792dec0929dbb6360a609fb00fa20bb16fc2 ]
We allocate only the first level of multilevel TCE tables for KVM already (alloc_userspace_copy==true), and the rest is allocated on demand. This is not enabled though for bare metal.
This removes the KVM limitation (implicit, via the alloc_userspace_copy parameter) and always allocates just the first level. The on-demand allocation of missing levels is already implemented.
As from now on DMA map might happen with disabled interrupts, this allocates TCEs with GFP_ATOMIC; otherwise lockdep reports errors 1]. In practice just a single page is allocated there so chances for failure are quite low.
To save time when creating a new clean table, this skips non-allocated indirect TCE entries in pnv_tce_free just like we already do in the VFIO IOMMU TCE driver.
This changes the default level number from 1 to 2 to reduce the amount of memory required for the default 32bit DMA window at the boot time. The default window size is up to 2GB which requires 4MB of TCEs which is unlikely to be used entirely or at all as most devices these days are 64bit capable so by switching to 2 levels by default we save 4032KB of RAM per a device.
While at this, add __GFP_NOWARN to alloc_pages_node() as the userspace can trigger this path via VFIO, see the failure and try creating a table again with different parameters which might succeed.
[1]: === BUG: sleeping function called from invalid context at mm/page_alloc.c:4596 in_atomic(): 1, irqs_disabled(): 1, pid: 1038, name: scsi_eh_1 2 locks held by scsi_eh_1/1038: #0: 000000005efd659a (&host->eh_mutex){+.+.}, at: ata_eh_acquire+0x34/0x80 #1: 0000000006cf56a6 (&(&host->lock)->rlock){....}, at: ata_exec_internal_sg+0xb0/0x5c0 irq event stamp: 500 hardirqs last enabled at (499): [<c000000000cb8a74>] _raw_spin_unlock_irqrestore+0x94/0xd0 hardirqs last disabled at (500): [<c000000000cb85c4>] _raw_spin_lock_irqsave+0x44/0x120 softirqs last enabled at (0): [<c000000000101120>] copy_process.isra.4.part.5+0x640/0x1a80 softirqs last disabled at (0): [<0000000000000000>] 0x0 CPU: 73 PID: 1038 Comm: scsi_eh_1 Not tainted 5.2.0-rc6-le_nv2_aikATfstn1-p1 #634 Call Trace: [c000003d064cef50] [c000000000c8e6c4] dump_stack+0xe8/0x164 (unreliable) [c000003d064cefa0] [c00000000014ed78] ___might_sleep+0x2f8/0x310 [c000003d064cf020] [c0000000003ca084] __alloc_pages_nodemask+0x2a4/0x1560 [c000003d064cf220] [c0000000000c2530] pnv_alloc_tce_level.isra.0+0x90/0x130 [c000003d064cf290] [c0000000000c2888] pnv_tce+0x128/0x3b0 [c000003d064cf360] [c0000000000c2c00] pnv_tce_build+0xb0/0xf0 [c000003d064cf3c0] [c0000000000bbd9c] pnv_ioda2_tce_build+0x3c/0xb0 [c000003d064cf400] [c00000000004cfe0] ppc_iommu_map_sg+0x210/0x550 [c000003d064cf510] [c00000000004b7a4] dma_iommu_map_sg+0x74/0xb0 [c000003d064cf530] [c000000000863944] ata_qc_issue+0x134/0x470 [c000003d064cf5b0] [c000000000863ec4] ata_exec_internal_sg+0x244/0x5c0 [c000003d064cf700] [c0000000008642d0] ata_exec_internal+0x90/0xe0 [c000003d064cf780] [c0000000008650ac] ata_dev_read_id+0x2ec/0x640 [c000003d064cf8d0] [c000000000878e28] ata_eh_recover+0x948/0x16d0 [c000003d064cfa10] [c00000000087d760] sata_pmp_error_handler+0x480/0xbf0 [c000003d064cfbc0] [c000000000884624] ahci_error_handler+0x74/0xe0 [c000003d064cfbf0] [c000000000879fa8] ata_scsi_port_error_handler+0x2d8/0x7c0 [c000003d064cfca0] [c00000000087a544] ata_scsi_error+0xb4/0x100 [c000003d064cfd00] [c000000000802450] scsi_error_handler+0x120/0x510 [c000003d064cfdb0] [c000000000140c48] kthread+0x1b8/0x1c0 [c000003d064cfe20] [c00000000000bd8c] ret_from_kernel_thread+0x5c/0x70 ata1: SATA link up 6.0 Gbps (SStatus 133 SControl 300) irq event stamp: 2305
======================================================== hardirqs last enabled at (2305): [<c00000000000e4c8>] fast_exc_return_irq+0x28/0x34 hardirqs last disabled at (2303): [<c000000000cb9fd0>] __do_softirq+0x4a0/0x654 WARNING: possible irq lock inversion dependency detected 5.2.0-rc6-le_nv2_aikATfstn1-p1 #634 Tainted: G W softirqs last enabled at (2304): [<c000000000cba054>] __do_softirq+0x524/0x654 softirqs last disabled at (2297): [<c00000000010f278>] irq_exit+0x128/0x180 -------------------------------------------------------- swapper/0/0 just changed the state of lock: 0000000006cf56a6 (&(&host->lock)->rlock){-...}, at: ahci_single_level_irq_intr+0xac/0x120 but this lock took another, HARDIRQ-unsafe lock in the past: (fs_reclaim){+.+.}
and interrupts could create inverse lock ordering between them.
other info that might help us debug this: Possible interrupt unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(fs_reclaim); local_irq_disable(); lock(&(&host->lock)->rlock); lock(fs_reclaim); <Interrupt> lock(&(&host->lock)->rlock);
*** DEADLOCK ***
no locks held by swapper/0/0.
the shortest dependencies between 2nd lock and 1st lock: -> (fs_reclaim){+.+.} ops: 167579 { HARDIRQ-ON-W at: lock_acquire+0xf8/0x2a0 fs_reclaim_acquire.part.23+0x44/0x60 kmem_cache_alloc_node_trace+0x80/0x590 alloc_desc+0x64/0x270 __irq_alloc_descs+0x2e4/0x3a0 irq_domain_alloc_descs+0xb0/0x150 irq_create_mapping+0x168/0x2c0 xics_smp_probe+0x2c/0x98 pnv_smp_probe+0x40/0x9c smp_prepare_cpus+0x524/0x6c4 kernel_init_freeable+0x1b4/0x650 kernel_init+0x2c/0x148 ret_from_kernel_thread+0x5c/0x70 SOFTIRQ-ON-W at: lock_acquire+0xf8/0x2a0 fs_reclaim_acquire.part.23+0x44/0x60 kmem_cache_alloc_node_trace+0x80/0x590 alloc_desc+0x64/0x270 __irq_alloc_descs+0x2e4/0x3a0 irq_domain_alloc_descs+0xb0/0x150 irq_create_mapping+0x168/0x2c0 xics_smp_probe+0x2c/0x98 pnv_smp_probe+0x40/0x9c smp_prepare_cpus+0x524/0x6c4 kernel_init_freeable+0x1b4/0x650 kernel_init+0x2c/0x148 ret_from_kernel_thread+0x5c/0x70 INITIAL USE at: lock_acquire+0xf8/0x2a0 fs_reclaim_acquire.part.23+0x44/0x60 kmem_cache_alloc_node_trace+0x80/0x590 alloc_desc+0x64/0x270 __irq_alloc_descs+0x2e4/0x3a0 irq_domain_alloc_descs+0xb0/0x150 irq_create_mapping+0x168/0x2c0 xics_smp_probe+0x2c/0x98 pnv_smp_probe+0x40/0x9c smp_prepare_cpus+0x524/0x6c4 kernel_init_freeable+0x1b4/0x650 kernel_init+0x2c/0x148 ret_from_kernel_thread+0x5c/0x70 } ===
Signed-off-by: Alexey Kardashevskiy aik@ozlabs.ru Reviewed-by: Alistair Popple alistair@popple.id.au Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20190718051139.74787-4-aik@ozlabs.ru Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/platforms/powernv/pci-ioda-tce.c | 20 +++++++++---------- arch/powerpc/platforms/powernv/pci.h | 2 +- 2 files changed, 11 insertions(+), 11 deletions(-)
diff --git a/arch/powerpc/platforms/powernv/pci-ioda-tce.c b/arch/powerpc/platforms/powernv/pci-ioda-tce.c index e28f03e1eb5eb..c75ec37bf0cda 100644 --- a/arch/powerpc/platforms/powernv/pci-ioda-tce.c +++ b/arch/powerpc/platforms/powernv/pci-ioda-tce.c @@ -36,7 +36,8 @@ static __be64 *pnv_alloc_tce_level(int nid, unsigned int shift) struct page *tce_mem = NULL; __be64 *addr;
- tce_mem = alloc_pages_node(nid, GFP_KERNEL, shift - PAGE_SHIFT); + tce_mem = alloc_pages_node(nid, GFP_ATOMIC | __GFP_NOWARN, + shift - PAGE_SHIFT); if (!tce_mem) { pr_err("Failed to allocate a TCE memory, level shift=%d\n", shift); @@ -161,6 +162,9 @@ void pnv_tce_free(struct iommu_table *tbl, long index, long npages)
if (ptce) *ptce = cpu_to_be64(0); + else + /* Skip the rest of the level */ + i |= tbl->it_level_size - 1; } }
@@ -260,7 +264,6 @@ long pnv_pci_ioda2_table_alloc_pages(int nid, __u64 bus_offset, unsigned int table_shift = max_t(unsigned int, entries_shift + 3, PAGE_SHIFT); const unsigned long tce_table_size = 1UL << table_shift; - unsigned int tmplevels = levels;
if (!levels || (levels > POWERNV_IOMMU_MAX_LEVELS)) return -EINVAL; @@ -268,9 +271,6 @@ long pnv_pci_ioda2_table_alloc_pages(int nid, __u64 bus_offset, if (!is_power_of_2(window_size)) return -EINVAL;
- if (alloc_userspace_copy && (window_size > (1ULL << 32))) - tmplevels = 1; - /* Adjust direct table size from window_size and levels */ entries_shift = (entries_shift + levels - 1) / levels; level_shift = entries_shift + 3; @@ -281,7 +281,7 @@ long pnv_pci_ioda2_table_alloc_pages(int nid, __u64 bus_offset,
/* Allocate TCE table */ addr = pnv_pci_ioda2_table_do_alloc_pages(nid, level_shift, - tmplevels, tce_table_size, &offset, &total_allocated); + 1, tce_table_size, &offset, &total_allocated);
/* addr==NULL means that the first level allocation failed */ if (!addr) @@ -292,18 +292,18 @@ long pnv_pci_ioda2_table_alloc_pages(int nid, __u64 bus_offset, * we did not allocate as much as we wanted, * release partially allocated table. */ - if (tmplevels == levels && offset < tce_table_size) + if (levels == 1 && offset < tce_table_size) goto free_tces_exit;
/* Allocate userspace view of the TCE table */ if (alloc_userspace_copy) { offset = 0; uas = pnv_pci_ioda2_table_do_alloc_pages(nid, level_shift, - tmplevels, tce_table_size, &offset, + 1, tce_table_size, &offset, &total_allocated_uas); if (!uas) goto free_tces_exit; - if (tmplevels == levels && (offset < tce_table_size || + if (levels == 1 && (offset < tce_table_size || total_allocated_uas != total_allocated)) goto free_uas_exit; } @@ -318,7 +318,7 @@ long pnv_pci_ioda2_table_alloc_pages(int nid, __u64 bus_offset,
pr_debug("Created TCE table: ws=%08llx ts=%lx @%08llx base=%lx uas=%p levels=%d/%d\n", window_size, tce_table_size, bus_offset, tbl->it_base, - tbl->it_userspace, tmplevels, levels); + tbl->it_userspace, 1, levels);
return 0;
diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h index be26ab3d99e01..33a52114267d0 100644 --- a/arch/powerpc/platforms/powernv/pci.h +++ b/arch/powerpc/platforms/powernv/pci.h @@ -225,7 +225,7 @@ extern struct iommu_table_group *pnv_npu_compound_attach( struct pnv_ioda_pe *pe);
/* pci-ioda-tce.c */ -#define POWERNV_IOMMU_DEFAULT_LEVELS 1 +#define POWERNV_IOMMU_DEFAULT_LEVELS 2 #define POWERNV_IOMMU_MAX_LEVELS 5
extern int pnv_tce_build(struct iommu_table *tbl, long index, long npages,