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Blame SOURCES/kvm-intel_iommu-Sanity-check-vfio-pci-config-on-machine-.patch

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From 3a528a458d4a2ba4236e98ef3f4efe5482323972 Mon Sep 17 00:00:00 2001
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From: Peter Xu <peterx@redhat.com>
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Date: Wed, 9 Oct 2019 12:39:44 +0100
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Subject: [PATCH 18/22] intel_iommu: Sanity check vfio-pci config on machine
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 init done
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RH-Author: Peter Xu <peterx@redhat.com>
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Message-id: <20191009123947.21505-3-peterx@redhat.com>
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Patchwork-id: 91347
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O-Subject: [RHEL-8.2.0 qemu-kvm PATCH 2/5] intel_iommu: Sanity check vfio-pci config on machine init done
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Bugzilla: 1738440
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Auger Eric <eric.auger@redhat.com>
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RH-Acked-by: Alex Williamson <alex.williamson@redhat.com>
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This check was previously only happened when the IOMMU is enabled in
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the guest.  It was always too late because the enabling of IOMMU
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normally only happens during the boot of guest OS.  It means that we
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can bail out and exit directly during the guest OS boots if the
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configuration of devices are not supported.  Or, if the guest didn't
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enable vIOMMU at all, then the user can use the guest normally but as
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long as it reconfigure the guest OS to enable the vIOMMU then reboot,
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the user will see the panic right after the reset when the next boot
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starts.
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Let's make this failure even earlier so that we force the user to use
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caching-mode for vfio-pci devices when with the vIOMMU.  So the user
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won't get surprise at least during execution of the guest, which seems
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a bit nicer.
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This will affect some user who didn't enable vIOMMU in the guest OS
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but was using vfio-pci and the vtd device in the past.  However I hope
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it's not a majority because not enabling vIOMMU with the device
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attached is actually meaningless.
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We still keep the old assertion for safety so far because the hotplug
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path could still reach it, so far.
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Reviewed-by: Eric Auger <eric.auger@redhat.com>
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Signed-off-by: Peter Xu <peterx@redhat.com>
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Message-Id: <20190916080718.3299-2-peterx@redhat.com>
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Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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(cherry picked from commit 28cf553afeb29b0c4f339c600171552a72a68cb7)
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Signed-off-by: Peter Xu <peterx@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 hw/i386/intel_iommu.c | 39 ++++++++++++++++++++++++++++++++++++---
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 1 file changed, 36 insertions(+), 3 deletions(-)
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diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
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index 22d2e52..44d19cc 100644
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--- a/hw/i386/intel_iommu.c
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+++ b/hw/i386/intel_iommu.c
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@@ -33,6 +33,7 @@
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 #include "hw/i386/x86-iommu.h"
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 #include "hw/pci-host/q35.h"
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 #include "sysemu/kvm.h"
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+#include "sysemu/sysemu.h"
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 #include "hw/i386/apic_internal.h"
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 #include "kvm_i386.h"
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 #include "trace.h"
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@@ -40,6 +41,13 @@
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 static void vtd_address_space_refresh_all(IntelIOMMUState *s);
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 static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n);
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+static void vtd_panic_require_caching_mode(void)
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+{
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+    error_report("We need to set caching-mode=on for intel-iommu to enable "
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+                 "device assignment with IOMMU protection.");
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+    exit(1);
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+}
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+
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 static void vtd_define_quad(IntelIOMMUState *s, hwaddr addr, uint64_t val,
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                             uint64_t wmask, uint64_t w1cmask)
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 {
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@@ -2554,9 +2562,7 @@ static void vtd_iommu_notify_flag_changed(IOMMUMemoryRegion *iommu,
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     IntelIOMMUState *s = vtd_as->iommu_state;
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     if (!s->caching_mode && new & IOMMU_NOTIFIER_MAP) {
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-        error_report("We need to set caching-mode=on for intel-iommu to enable "
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-                     "device assignment with IOMMU protection.");
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-        exit(1);
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+        vtd_panic_require_caching_mode();
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     }
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     /* Update per-address-space notifier flags */
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@@ -3303,6 +3309,32 @@ static bool vtd_decide_config(IntelIOMMUState *s, Error **errp)
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     return true;
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 }
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+static int vtd_machine_done_notify_one(Object *child, void *unused)
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+{
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+    IntelIOMMUState *iommu = INTEL_IOMMU_DEVICE(x86_iommu_get_default());
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+
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+    /*
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+     * We hard-coded here because vfio-pci is the only special case
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+     * here.  Let's be more elegant in the future when we can, but so
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+     * far there seems to be no better way.
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+     */
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+    if (object_dynamic_cast(child, "vfio-pci") && !iommu->caching_mode) {
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+        vtd_panic_require_caching_mode();
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+    }
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+
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+    return 0;
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+}
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+
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+static void vtd_machine_done_hook(Notifier *notifier, void *unused)
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+{
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+    object_child_foreach_recursive(object_get_root(),
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+                                   vtd_machine_done_notify_one, NULL);
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+}
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+
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+static Notifier vtd_machine_done_notify = {
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+    .notify = vtd_machine_done_hook,
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+};
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+
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 static void vtd_realize(DeviceState *dev, Error **errp)
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 {
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     MachineState *ms = MACHINE(qdev_get_machine());
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@@ -3333,6 +3365,7 @@ static void vtd_realize(DeviceState *dev, Error **errp)
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     pci_setup_iommu(bus, vtd_host_dma_iommu, dev);
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     /* Pseudo address space under root PCI bus. */
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     pcms->ioapic_as = vtd_host_dma_iommu(bus, s, Q35_PSEUDO_DEVFN_IOAPIC);
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+    qemu_add_machine_init_done_notifier(&vtd_machine_done_notify);
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 }
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 static void vtd_class_init(ObjectClass *klass, void *data)
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-- 
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1.8.3.1
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