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PCI: MSI: Remove unsafe and unnecessary hardware access 

During suspend on an SMP system, {read,write}_msi_msg_desc() may be
called to mask and unmask interrupts on a device that is already in a
reduced power state.  At this point memory-mapped registers including
MSI-X tables are not accessible, and config space may not be fully
functional either.

While a device is in a reduced power state its interrupts are
effectively masked and its MSI(-X) state will be restored when it is
brought back to D0.  Therefore these functions can simply read and
write msi_desc::msg for devices not in D0.

Further, read_msi_msg_desc() should only ever be used to update a
previously written message, so it can always read msi_desc::msg
and never needs to touch the hardware.

Tested-by: "Michael Chan" <mchan@broadcom.com>
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
This commit is contained in:
Ben Hutchings 2010-06-17 20:16:36 +01:00 committed by Jesse Barnes
parent ea5f9fc589
commit fcd097f31a
1 changed files with 11 additions and 23 deletions
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34
drivers/pci/msi.c
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@ -196,30 +196,15 @@ void unmask_msi_irq(unsigned int irq)
void read_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg)
{
struct msi_desc *entry = get_irq_desc_msi(desc);
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;
/* 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
* valid messages are not all-zeroes. */
BUG_ON(!(entry->msg.address_hi | entry->msg.address_lo |
entry->msg.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;
}
*msg = entry->msg;
}
void read_msi_msg(unsigned int irq, struct msi_msg *msg)
@ -232,7 +217,10 @@ void read_msi_msg(unsigned int irq, struct msi_msg *msg)
void write_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg)
{
struct msi_desc *entry = get_irq_desc_msi(desc);
if (entry->msi_attrib.is_msix) {
if (entry->dev->current_state != PCI_D0) {
/* Don't touch the hardware now */
} else if (entry->msi_attrib.is_msix) {
void __iomem *base;
base = entry->mask_base +
entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE;