kernel.git/drivers/xen, branch linux-5.7.y

xen: don't reschedule in preemption off sections

2020-08-26T09:42:24Z

For support of long running hypercalls xen_maybe_preempt_hcall() is calling cond_resched() in case a hypercall marked as preemptible has been interrupted. Normally this is no problem, as only hypercalls done via some ioctl()s are marked to be preemptible. In rare cases when during such a preemptible hypercall an interrupt occurs and any softirq action is started from irq_exit(), a further hypercall issued by the softirq handler will be regarded to be preemptible, too. This might lead to rescheduling in spite of the softirq handler potentially having set preempt_disable(), leading to splats like: BUG: sleeping function called from invalid context at drivers/xen/preempt.c:37 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 20775, name: xl INFO: lockdep is turned off. CPU: 1 PID: 20775 Comm: xl Tainted: G D W 5.4.46-1_prgmr_debug.el7.x86_64 #1 Call Trace: dump_stack+0x8f/0xd0 ___might_sleep.cold.76+0xb2/0x103 xen_maybe_preempt_hcall+0x48/0x70 xen_do_hypervisor_callback+0x37/0x40 RIP: e030:xen_hypercall_xen_version+0xa/0x20 Code: ... RSP: e02b:ffffc900400dcc30 EFLAGS: 00000246 RAX: 000000000004000d RBX: 0000000000000200 RCX: ffffffff8100122a RDX: ffff88812e788000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffffff83ee3ad0 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000246 R12: ffff8881824aa0b0 R13: 0000000865496000 R14: 0000000865496000 R15: ffff88815d040000 ? xen_hypercall_xen_version+0xa/0x20 ? xen_force_evtchn_callback+0x9/0x10 ? check_events+0x12/0x20 ? xen_restore_fl_direct+0x1f/0x20 ? _raw_spin_unlock_irqrestore+0x53/0x60 ? debug_dma_sync_single_for_cpu+0x91/0xc0 ? _raw_spin_unlock_irqrestore+0x53/0x60 ? xen_swiotlb_sync_single_for_cpu+0x3d/0x140 ? mlx4_en_process_rx_cq+0x6b6/0x1110 [mlx4_en] ? mlx4_en_poll_rx_cq+0x64/0x100 [mlx4_en] ? net_rx_action+0x151/0x4a0 ? __do_softirq+0xed/0x55b ? irq_exit+0xea/0x100 ? xen_evtchn_do_upcall+0x2c/0x40 ? xen_do_hypervisor_callback+0x29/0x40 ? xen_hypercall_domctl+0xa/0x20 ? xen_hypercall_domctl+0x8/0x20 ? privcmd_ioctl+0x221/0x990 [xen_privcmd] ? do_vfs_ioctl+0xa5/0x6f0 ? ksys_ioctl+0x60/0x90 ? trace_hardirqs_off_thunk+0x1a/0x20 ? __x64_sys_ioctl+0x16/0x20 ? do_syscall_64+0x62/0x250 ? entry_SYSCALL_64_after_hwframe+0x49/0xbe Fix that by testing preempt_count() before calling cond_resched(). In kernel 5.8 this can't happen any more due to the entry code rework (more than 100 patches, so not a candidate for backporting). The issue was introduced in kernel 4.3, so this patch should go into all stable kernels in [4.3 ... 5.7]. Reported-by: Sarah Newman Fixes: 0fa2f5cb2b0ecd8 ("sched/preempt, xen: Use need_resched() instead of should_resched()") Cc: Sarah Newman Cc: stable@vger.kernel.org Signed-off-by: Juergen Gross Tested-by: Chris Brannon Signed-off-by: Greg Kroah-Hartman

swiotlb-xen: use vmalloc_to_page on vmalloc virt addresses

2020-08-26T09:42:12Z

[ Upstream commit 8b1e868f66076490189a36d984fcce286cdd6295 ] xen_alloc_coherent_pages might return pages for which virt_to_phys and virt_to_page don't work, e.g. ioremap'ed pages. So in xen_swiotlb_free_coherent we can't assume that virt_to_page works. Instead add a is_vmalloc_addr check and use vmalloc_to_page on vmalloc virt addresses. This patch fixes the following crash at boot on RPi4 (the underlying issue is not RPi4 specific): https://marc.info/?l=xen-devel&m=158862573216800 Signed-off-by: Boris Ostrovsky Signed-off-by: Stefano Stabellini Reviewed-by: Boris Ostrovsky Tested-by: Corey Minyard Tested-by: Roman Shaposhnik Link: https://lore.kernel.org/r/20200710223427.6897-1-sstabellini@kernel.org Signed-off-by: Juergen Gross Signed-off-by: Sasha Levin

xen/gntdev: Fix dmabuf import with non-zero sgt offset

2020-08-19T06:24:19Z

commit 5fa4e6f1c2d8c9a4e47e1931b42893172d388f2b upstream. It is possible that the scatter-gather table during dmabuf import has non-zero offset of the data, but user-space doesn't expect that. Fix this by failing the import, so user-space doesn't access wrong data. Fixes: bf8dc55b1358 ("xen/gntdev: Implement dma-buf import functionality") Signed-off-by: Oleksandr Andrushchenko Acked-by: Juergen Gross Cc: Link: https://lore.kernel.org/r/20200813062113.11030-2-andr2000@gmail.com Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman

xen/balloon: make the balloon wait interruptible

2020-08-19T06:24:18Z

commit 88a479ff6ef8af7f07e11593d58befc644244ff7 upstream. So it can be killed, or else processes can get hung indefinitely waiting for balloon pages. Signed-off-by: Roger Pau Monné Reviewed-by: Juergen Gross Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200727091342.52325-3-roger.pau@citrix.com Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman

xen/balloon: fix accounting in alloc_xenballooned_pages error path

2020-08-19T06:24:18Z

commit 1951fa33ec259abdf3497bfee7b63e7ddbb1a394 upstream. target_unpopulated is incremented with nr_pages at the start of the function, but the call to free_xenballooned_pages will only subtract pgno number of pages, and thus the rest need to be subtracted before returning or else accounting will be skewed. Signed-off-by: Roger Pau Monné Reviewed-by: Juergen Gross Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200727091342.52325-2-roger.pau@citrix.com Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman

xen/xenbus: Fix a double free in xenbus_map_ring_pv()

2020-07-22T07:34:04Z

[ Upstream commit ba8c423488974f02b538e9dc1730f0334f9b85aa ] When there is an error the caller frees "info->node" so the free here will result in a double free. We should just delete first kfree(). Fixes: 3848e4e0a32a ("xen/xenbus: avoid large structs and arrays on the stack") Signed-off-by: Dan Carpenter Link: https://lore.kernel.org/r/20200710113610.GA92345@mwanda Reviewed-by: Juergen Gross Signed-off-by: Boris Ostrovsky Signed-off-by: Sasha Levin

xen/xenbus: let xenbus_map_ring_valloc() return errno values only

2020-07-22T07:34:01Z

[ Upstream commit 578c1bb9056263ad3c9e09746b3d6e4daf63bdb0 ] Today xenbus_map_ring_valloc() can return either a negative errno value (-ENOMEM or -EINVAL) or a grant status value. This is a mess as e.g -ENOMEM and GNTST_eagain have the same numeric value. Fix that by turning all grant mapping errors into -ENOENT. This is no problem as all callers of xenbus_map_ring_valloc() only use the return value to print an error message, and in case of mapping errors the grant status value has already been printed by __xenbus_map_ring() before. Signed-off-by: Juergen Gross Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/20200701121638.19840-3-jgross@suse.com Signed-off-by: Boris Ostrovsky Signed-off-by: Sasha Levin

xen/xenbus: avoid large structs and arrays on the stack

2020-07-22T07:34:01Z

[ Upstream commit 3848e4e0a32afb96dc3b84e1358c3b9d103c6a2c ] xenbus_map_ring_valloc() and its sub-functions are putting quite large structs and arrays on the stack. This is problematic at runtime, but might also result in build failures (e.g. with clang due to the option -Werror,-Wframe-larger-than=... used). Fix that by moving most of the data from the stack into a dynamically allocated struct. Performance is no issue here, as xenbus_map_ring_valloc() is used only when adding a new PV device to a backend driver. While at it move some duplicated code from pv/hvm specific mapping functions to the single caller. Reported-by: Arnd Bergmann Signed-off-by: Juergen Gross Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/20200701121638.19840-2-jgross@suse.com Signed-off-by: Boris Ostrovsky Signed-off-by: Sasha Levin

xen/cpuhotplug: Fix initial CPU offlining for PV(H) guests

2020-06-24T15:48:53Z

[ Upstream commit c54b071c192dfe8061336f650ceaf358e6386e0b ] Commit a926f81d2f6c ("xen/cpuhotplug: Replace cpu_up/down() with device_online/offline()") replaced cpu_down() with device_offline() call which requires that the CPU has been registered before. This registration, however, happens later from topology_init() which is called as subsys_initcall(). setup_vcpu_hotplug_event(), on the other hand, is invoked earlier, during arch_initcall(). As result, booting a PV(H) guest with vcpus < maxvcpus causes a crash. Move setup_vcpu_hotplug_event() (and therefore setup_cpu_watcher()) to late_initcall(). In addition, instead of performing all offlining steps in setup_cpu_watcher() simply call disable_hotplug_cpu(). Fixes: a926f81d2f6c (xen/cpuhotplug: Replace cpu_up/down() with device_online/offline()" Signed-off-by: Boris Ostrovsky Link: https://lore.kernel.org/r/1588976923-3667-1-git-send-email-boris.ostrovsky@oracle.com Reviewed-by: Juergen Gross Signed-off-by: Boris Ostrovsky Signed-off-by: Sasha Levin

xen/pvcalls-back: test for errors when calling backend_connect()

2020-06-17T14:43:04Z

commit c8d70a29d6bbc956013f3401f92a4431a9385a3c upstream. backend_connect() can fail, so switch the device to connected only if no error occurred. Fixes: 0a9c75c2c7258f2 ("xen/pvcalls: xenbus state handling") Cc: stable@vger.kernel.org Signed-off-by: Juergen Gross Link: https://lore.kernel.org/r/20200511074231.19794-1-jgross@suse.com Reviewed-by: Stefano Stabellini Signed-off-by: Boris Ostrovsky Signed-off-by: Greg Kroah-Hartman