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    Subject[018/129] PCI: MSI: Restore read_msi_msg_desc(); add get_cached_msi_msg_desc()
    2.6.35-stable review patch.  If anyone has any objections, please let us know.

    ------------------

    From: Ben Hutchings <bhutchings@solarflare.com>

    commit 30da55242818a8ca08583188ebcbaccd283ad4d9 upstream.

    commit 2ca1af9aa3285c6a5f103ed31ad09f7399fc65d7 "PCI: MSI: Remove
    unsafe and unnecessary hardware access" changed read_msi_msg_desc() to
    return the last MSI message written instead of reading it from the
    device, since it may be called while the device is in a reduced
    power state.

    However, the pSeries platform code really does need to read messages
    from the device, since they are initially written by firmware.
    Therefore:
    - Restore the previous behaviour of read_msi_msg_desc()
    - Add new functions get_cached_msi_msg{,_desc}() which return the
    last MSI message written
    - Use the new functions where appropriate

    Acked-by: Michael Ellerman <michael@ellerman.id.au>
    Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
    Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    arch/ia64/kernel/msi_ia64.c | 2 -
    arch/ia64/sn/kernel/msi_sn.c | 2 -
    arch/x86/kernel/apic/io_apic.c | 2 -
    drivers/pci/msi.c | 47 ++++++++++++++++++++++++++++++++++++-----
    include/linux/msi.h | 2 +
    5 files changed, 47 insertions(+), 8 deletions(-)

    --- a/arch/ia64/kernel/msi_ia64.c
    +++ b/arch/ia64/kernel/msi_ia64.c
    @@ -25,7 +25,7 @@ static int ia64_set_msi_irq_affinity(uns
    if (irq_prepare_move(irq, cpu))
    return -1;

    - read_msi_msg(irq, &msg);
    + get_cached_msi_msg(irq, &msg);

    addr = msg.address_lo;
    addr &= MSI_ADDR_DEST_ID_MASK;
    --- a/arch/ia64/sn/kernel/msi_sn.c
    +++ b/arch/ia64/sn/kernel/msi_sn.c
    @@ -175,7 +175,7 @@ static int sn_set_msi_irq_affinity(unsig
    * Release XIO resources for the old MSI PCI address
    */

    - read_msi_msg(irq, &msg);
    + get_cached_msi_msg(irq, &msg);
    sn_pdev = (struct pcidev_info *)sn_irq_info->irq_pciioinfo;
    pdev = sn_pdev->pdi_linux_pcidev;
    provider = SN_PCIDEV_BUSPROVIDER(pdev);
    --- a/arch/x86/kernel/apic/io_apic.c
    +++ b/arch/x86/kernel/apic/io_apic.c
    @@ -3399,7 +3399,7 @@ static int set_msi_irq_affinity(unsigned

    cfg = desc->chip_data;

    - read_msi_msg_desc(desc, &msg);
    + get_cached_msi_msg_desc(desc, &msg);

    msg.data &= ~MSI_DATA_VECTOR_MASK;
    msg.data |= MSI_DATA_VECTOR(cfg->vector);
    --- a/drivers/pci/msi.c
    +++ b/drivers/pci/msi.c
    @@ -197,9 +197,46 @@ void read_msi_msg_desc(struct irq_desc *
    {
    struct msi_desc *entry = get_irq_desc_msi(desc);

    - /* We do not touch the hardware (which may not even be
    - * accessible at the moment) but return the last message
    - * written. Assert that this is valid, assuming that
    + BUG_ON(entry->dev->current_state != PCI_D0);
    +
    + if (entry->msi_attrib.is_msix) {
    + void __iomem *base = entry->mask_base +
    + entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE;
    +
    + msg->address_lo = readl(base + PCI_MSIX_ENTRY_LOWER_ADDR);
    + msg->address_hi = readl(base + PCI_MSIX_ENTRY_UPPER_ADDR);
    + msg->data = readl(base + PCI_MSIX_ENTRY_DATA);
    + } else {
    + struct pci_dev *dev = entry->dev;
    + int pos = entry->msi_attrib.pos;
    + u16 data;
    +
    + pci_read_config_dword(dev, msi_lower_address_reg(pos),
    + &msg->address_lo);
    + if (entry->msi_attrib.is_64) {
    + pci_read_config_dword(dev, msi_upper_address_reg(pos),
    + &msg->address_hi);
    + pci_read_config_word(dev, msi_data_reg(pos, 1), &data);
    + } else {
    + msg->address_hi = 0;
    + pci_read_config_word(dev, msi_data_reg(pos, 0), &data);
    + }
    + msg->data = data;
    + }
    +}
    +
    +void read_msi_msg(unsigned int irq, struct msi_msg *msg)
    +{
    + struct irq_desc *desc = irq_to_desc(irq);
    +
    + read_msi_msg_desc(desc, msg);
    +}
    +
    +void get_cached_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg)
    +{
    + struct msi_desc *entry = get_irq_desc_msi(desc);
    +
    + /* Assert that the cache is valid, assuming that
    * valid messages are not all-zeroes. */
    BUG_ON(!(entry->msg.address_hi | entry->msg.address_lo |
    entry->msg.data));
    @@ -207,11 +244,11 @@ void read_msi_msg_desc(struct irq_desc *
    *msg = entry->msg;
    }

    -void read_msi_msg(unsigned int irq, struct msi_msg *msg)
    +void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg)
    {
    struct irq_desc *desc = irq_to_desc(irq);

    - read_msi_msg_desc(desc, msg);
    + get_cached_msi_msg_desc(desc, msg);
    }

    void write_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg)
    --- a/include/linux/msi.h
    +++ b/include/linux/msi.h
    @@ -14,8 +14,10 @@ struct irq_desc;
    extern void mask_msi_irq(unsigned int irq);
    extern void unmask_msi_irq(unsigned int irq);
    extern void read_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg);
    +extern void get_cached_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg);
    extern void write_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg);
    extern void read_msi_msg(unsigned int irq, struct msi_msg *msg);
    +extern void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);
    extern void write_msi_msg(unsigned int irq, struct msi_msg *msg);

    struct msi_desc {



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