From 61256a82ce78f40222455becb8850b5f5ebb5d72 Mon Sep 17 00:00:00 2001 From: Igor Mammedov Date: Tue, 18 Apr 2023 11:04:49 +0200 Subject: [PATCH 1/3] acpi: pcihp: allow repeating hot-unplug requests RH-Author: Igor Mammedov RH-MergeRequest: 159: acpi: pcihp: allow repeating hot-unplug requests RH-Bugzilla: 2087047 RH-Acked-by: Ani Sinha RH-Acked-by: Julia Suvorova RH-Acked-by: Miroslav Rezanina RH-Acked-by: MST RH-Commit: [1/1] 9c597232466b27d91f127ee6004322d6ba69755f (imammedo/qemu-kvm-c-9-s-imam) with Q35 using ACPI PCI hotplug by default, user's request to unplug device is ignored when it's issued before guest OS has been booted. And any additional attempt to request device hot-unplug afterwards results in following error: "Device XYZ is already in the process of unplug" arguably it can be considered as a regression introduced by [2], before which it was possible to issue unplug request multiple times. Accept new uplug requests after timeout (1ms). This brings ACPI PCI hotplug on par with native PCIe unplug behavior [1] and allows user to repeat unplug requests at propper times. Set expire timeout to arbitrary 1msec so user won't be able to flood guest with SCI interrupts by calling device_del in tight loop. PS: ACPI spec doesn't mandate what OSPM can do with GPEx.status bits set before it's booted => it's impl. depended. Status bits may be retained (I tested with one Windows version) or cleared (Linux since 2.6 kernel times) during guest's ACPI subsystem initialization. Clearing status bits (though not wrong per se) hides the unplug event from guest, and it's upto user to repeat device_del later when guest is able to handle unplug requests. 1) 18416c62e3 ("pcie: expire pending delete") 2) Fixes: cce8944cc9ef ("qdev-monitor: Forbid repeated device_del") Signed-off-by: Igor Mammedov Acked-by: Gerd Hoffmann CC: mst@redhat.com CC: anisinha@redhat.com CC: jusual@redhat.com CC: kraxel@redhat.com Message-Id: <20230418090449.2155757-1-imammedo@redhat.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Reviewed-by: Ani Sinha (cherry picked from commit 0f689cf5ada4d5df5ab95c7f7aa9fc221afa855d) Signed-off-by: Igor Mammedov --- hw/acpi/pcihp.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c index dcfb779a7a..cdd6f775a1 100644 --- a/hw/acpi/pcihp.c +++ b/hw/acpi/pcihp.c @@ -357,6 +357,16 @@ void acpi_pcihp_device_unplug_request_cb(HotplugHandler *hotplug_dev, * acpi_pcihp_eject_slot() when the operation is completed. */ pdev->qdev.pending_deleted_event = true; + /* if unplug was requested before OSPM is initialized, + * linux kernel will clear GPE0.sts[] bits during boot, which effectively + * hides unplug event. And than followup qmp_device_del() calls remain + * blocked by above flag permanently. + * Unblock qmp_device_del() by setting expire limit, so user can + * repeat unplug request later when OSPM has been booted. + */ + pdev->qdev.pending_deleted_expires_ms = + qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL); /* 1 msec */ + s->acpi_pcihp_pci_status[bsel].down |= (1U << slot); acpi_send_event(DEVICE(hotplug_dev), ACPI_PCI_HOTPLUG_STATUS); } -- 2.39.1