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    Subject[PATCH 5.9 529/757] vfio/pci: Decouple PCI_COMMAND_MEMORY bit checks from is_virtfn
    Date
    From: Matthew Rosato <mjrosato@linux.ibm.com>

    [ Upstream commit 515ecd5368f1510152fa4f9b9ce55b66ac56c334 ]

    While it is true that devices with is_virtfn=1 will have a Memory Space
    Enable bit that is hard-wired to 0, this is not the only case where we
    see this behavior -- For example some bare-metal hypervisors lack
    Memory Space Enable bit emulation for devices not setting is_virtfn
    (s390). Fix this by instead checking for the newly-added
    no_command_memory bit which directly denotes the need for
    PCI_COMMAND_MEMORY emulation in vfio.

    Fixes: abafbc551fdd ("vfio-pci: Invalidate mmaps and block MMIO access on disabled memory")
    Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
    Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
    Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
    Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/vfio/pci/vfio_pci_config.c | 24 ++++++++++++++----------
    1 file changed, 14 insertions(+), 10 deletions(-)

    diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c
    index d98843feddce0..5076d0155bc3f 100644
    --- a/drivers/vfio/pci/vfio_pci_config.c
    +++ b/drivers/vfio/pci/vfio_pci_config.c
    @@ -406,7 +406,7 @@ bool __vfio_pci_memory_enabled(struct vfio_pci_device *vdev)
    * PF SR-IOV capability, there's therefore no need to trigger
    * faults based on the virtual value.
    */
    - return pdev->is_virtfn || (cmd & PCI_COMMAND_MEMORY);
    + return pdev->no_command_memory || (cmd & PCI_COMMAND_MEMORY);
    }

    /*
    @@ -520,8 +520,8 @@ static int vfio_basic_config_read(struct vfio_pci_device *vdev, int pos,

    count = vfio_default_config_read(vdev, pos, count, perm, offset, val);

    - /* Mask in virtual memory enable for SR-IOV devices */
    - if (offset == PCI_COMMAND && vdev->pdev->is_virtfn) {
    + /* Mask in virtual memory enable */
    + if (offset == PCI_COMMAND && vdev->pdev->no_command_memory) {
    u16 cmd = le16_to_cpu(*(__le16 *)&vdev->vconfig[PCI_COMMAND]);
    u32 tmp_val = le32_to_cpu(*val);

    @@ -589,9 +589,11 @@ static int vfio_basic_config_write(struct vfio_pci_device *vdev, int pos,
    * shows it disabled (phys_mem/io, then the device has
    * undergone some kind of backdoor reset and needs to be
    * restored before we allow it to enable the bars.
    - * SR-IOV devices will trigger this, but we catch them later
    + * SR-IOV devices will trigger this - for mem enable let's
    + * catch this now and for io enable it will be caught later
    */
    - if ((new_mem && virt_mem && !phys_mem) ||
    + if ((new_mem && virt_mem && !phys_mem &&
    + !pdev->no_command_memory) ||
    (new_io && virt_io && !phys_io) ||
    vfio_need_bar_restore(vdev))
    vfio_bar_restore(vdev);
    @@ -1734,12 +1736,14 @@ int vfio_config_init(struct vfio_pci_device *vdev)
    vconfig[PCI_INTERRUPT_PIN]);

    vconfig[PCI_INTERRUPT_PIN] = 0; /* Gratuitous for good VFs */
    -
    + }
    + if (pdev->no_command_memory) {
    /*
    - * VFs do no implement the memory enable bit of the COMMAND
    - * register therefore we'll not have it set in our initial
    - * copy of config space after pci_enable_device(). For
    - * consistency with PFs, set the virtual enable bit here.
    + * VFs and devices that set pdev->no_command_memory do not
    + * implement the memory enable bit of the COMMAND register
    + * therefore we'll not have it set in our initial copy of
    + * config space after pci_enable_device(). For consistency
    + * with PFs, set the virtual enable bit here.
    */
    *(__le16 *)&vconfig[PCI_COMMAND] |=
    cpu_to_le16(PCI_COMMAND_MEMORY);
    --
    2.25.1


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