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Code Issues Releases Activity

Rework pass through changes in r305485 to be safer.

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Specifically, devices that do not support PCI-e FLR and were not
gracefully shutdown by the guest OS could continue to issue DMA
requests after the VM was terminated.  The changes in r305485 meant
that those DMA requests were completed against the host's memory which
could result in random memory corruption.  Instead, leave ppt devices
that are not attached to a VM disabled in the IOMMU and only restore
the devices to the host domain if the ppt(4) driver is detached from a
device.

As an added safety belt, disable busmastering for a pass-through device
when before adding it to the host domain during ppt(4) detach.

PR:		222937
Tested by:	Harry Schmalzbauer <freebsd@omnilan.de>
Reviewed by:	grehan
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D12661
This commit is contained in:
John Baldwin 2017-10-27 14:57:14 +00:00
parent 1c05a6ea6b
commit 6db55a0f3a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=325039
2 changed files with 14 additions and 3 deletions
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12
sys/amd64/vmm/io/iommu.c
View File

@ -174,6 +174,7 @@ iommu_init(void)
{
int error, bus, slot, func;
vm_paddr_t maxaddr;
devclass_t dc;
device_t dev;
if (!iommu_enable)
@ -214,6 +215,7 @@ iommu_init(void)
add_tag = EVENTHANDLER_REGISTER(pci_add_device, iommu_pci_add, NULL, 0);
delete_tag = EVENTHANDLER_REGISTER(pci_delete_device, iommu_pci_delete,
NULL, 0);
dc = devclass_find("ppt");
for (bus = 0; bus <= PCI_BUSMAX; bus++) {
for (slot = 0; slot <= PCI_SLOTMAX; slot++) {
for (func = 0; func <= PCI_FUNCMAX; func++) {
@ -221,7 +223,15 @@ iommu_init(void)
if (dev == NULL)
continue;
/* Everything belongs to the host domain. */
/* Skip passthrough devices. */
if (dc != NULL &&
device_get_devclass(dev) == dc)
continue;
/*
* Everything else belongs to the host
* domain.
*/
iommu_add_device(host_domain,
pci_get_rid(dev));
}

5
sys/amd64/vmm/io/ppt.c
View File

@ -154,6 +154,7 @@ ppt_attach(device_t dev)
ppt = device_get_softc(dev);
iommu_remove_device(iommu_host_domain(), pci_get_rid(dev));
num_pptdevs++;
TAILQ_INSERT_TAIL(&pptdev_list, ppt, next);
ppt->dev = dev;
@ -175,6 +176,8 @@ ppt_detach(device_t dev)
return (EBUSY);
num_pptdevs--;
TAILQ_REMOVE(&pptdev_list, ppt, next);
pci_disable_busmaster(dev);
iommu_add_device(iommu_host_domain(), pci_get_rid(dev));
return (0);
}
@ -368,7 +371,6 @@ ppt_assign_device(struct vm *vm, int bus, int slot, int func)
true);
pci_restore_state(ppt->dev);
ppt->vm = vm;
iommu_remove_device(iommu_host_domain(), pci_get_rid(ppt->dev));
iommu_add_device(vm_iommu_domain(vm), pci_get_rid(ppt->dev));
return (0);
}
@ -397,7 +399,6 @@ ppt_unassign_device(struct vm *vm, int bus, int slot, int func)
ppt_teardown_msi(ppt);
ppt_teardown_msix(ppt);
iommu_remove_device(vm_iommu_domain(vm), pci_get_rid(ppt->dev));
iommu_add_device(iommu_host_domain(), pci_get_rid(ppt->dev));
ppt->vm = NULL;
return (0);
}