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s390/pci: improve unreg_ioat error handling

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DMA tables are freed in zpci_dma_exit_device regardless of the return
code of zpci_unregister_ioat. This could lead to a use after free. On
the other hand during function hot-unplug, zpci_unregister_ioat will
always fail since the function is already gone.

So let zpci_unregister_ioat report success when the function is gone
but don't cleanup the dma table when a function could still have it
in access.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Sebastian Ott 2017-06-10 14:10:00 +02:00 committed by Martin Schwidefsky
parent 4dfbd3efe3
commit 7257083491
2 changed files with 17 additions and 6 deletions
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19
arch/s390/pci/pci.c
View File

@ -161,19 +161,28 @@ static int mod_pci(struct zpci_dev *zdev, int fn, u8 dmaas, struct mod_pci_args
int zpci_register_ioat(struct zpci_dev *zdev, u8 dmaas,
u64 base, u64 limit, u64 iota)
{
struct mod_pci_args args = { base, limit, iota, 0 };
u64 req = ZPCI_CREATE_REQ(zdev->fh, dmaas, ZPCI_MOD_FC_REG_IOAT);
struct zpci_fib fib = {0};
u8 status;
WARN_ON_ONCE(iota & 0x3fff);
args.iota |= ZPCI_IOTA_RTTO_FLAG;
return mod_pci(zdev, ZPCI_MOD_FC_REG_IOAT, dmaas, &args);
fib.pba = base;
fib.pal = limit;
fib.iota = iota | ZPCI_IOTA_RTTO_FLAG;
return zpci_mod_fc(req, &fib, &status) ? -EIO : 0;
}
/* Modify PCI: Unregister I/O address translation parameters */
int zpci_unregister_ioat(struct zpci_dev *zdev, u8 dmaas)
{
struct mod_pci_args args = { 0, 0, 0, 0 };
u64 req = ZPCI_CREATE_REQ(zdev->fh, dmaas, ZPCI_MOD_FC_DEREG_IOAT);
struct zpci_fib fib = {0};
u8 cc, status;
return mod_pci(zdev, ZPCI_MOD_FC_DEREG_IOAT, dmaas, &args);
cc = zpci_mod_fc(req, &fib, &status);
if (cc == 3) /* Function already gone. */
cc = 0;
return cc ? -EIO : 0;
}
/* Modify PCI: Set PCI function measurement parameters */

4
arch/s390/pci/pci_dma.c
View File

@ -601,7 +601,9 @@ void zpci_dma_exit_device(struct zpci_dev *zdev)
*/
WARN_ON(zdev->s390_domain);
zpci_unregister_ioat(zdev, 0);
if (zpci_unregister_ioat(zdev, 0))
return;
dma_cleanup_tables(zdev->dma_table);
zdev->dma_table = NULL;
vfree(zdev->iommu_bitmap);