Patch "PCI: designware-ep: Fix ->get_msi() to check MSI_EN bit" has been added to the 4.15-stable tree

This is a note to let you know that I've just added the patch titled

    PCI: designware-ep: Fix ->get_msi() to check MSI_EN bit

to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
pci-designware-ep-fix-get_msi-to-check-msi_en-bit.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Kishon Vijay Abraham I <[email protected]>
Date: Tue, 19 Dec 2017 15:25:41 +0530
Subject: PCI: designware-ep: Fix ->get_msi() to check MSI_EN bit

From: Kishon Vijay Abraham I <[email protected]>

[ Upstream commit a134a457ed985dca8cce7ac4ea66129ea70eba73 ]

->get_msi() now checks MSI_EN bit in the MSI CAPABILITY register to find whether the host supports MSI instead of using the MSI ADDRESS in the MSI CAPABILITY register.

This fixes the issue with the following sequence
'modprobe pci_endpoint_test' enables MSI
'rmmod pci_endpoint_test' disables MSI but MSI address (in EP's
capability register) has a valid value
'modprobe pci_endpoint_test no_msi=1' - Since MSI address (in EP's
capability register) has a valid value (set during the previous insertion of the module), EP thinks host supports MSI.

---
 drivers/pci/dwc/pcie-designware-ep.c |   12 +++---------
 drivers/pci/dwc/pcie-designware.h    |    1 +
 2 files changed, 4 insertions(+), 9 deletions(-)

@@ -197,20 +197,14 @@ static int dw_pcie_ep_map_addr(struct pc
 static int dw_pcie_ep_get_msi(struct pci_epc *epc)
 {
 	int val;
-	u32 lower_addr;
-	u32 upper_addr;
 	struct dw_pcie_ep *ep = epc_get_drvdata(epc);
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
 
-	val = dw_pcie_readb_dbi(pci, MSI_MESSAGE_CONTROL);
-	val = (val & MSI_CAP_MME_MASK) >> MSI_CAP_MME_SHIFT;
-
-	lower_addr = dw_pcie_readl_dbi(pci, MSI_MESSAGE_ADDR_L32);
-	upper_addr = dw_pcie_readl_dbi(pci, MSI_MESSAGE_ADDR_U32);
-
-	if (!(lower_addr || upper_addr))
+	val = dw_pcie_readw_dbi(pci, MSI_MESSAGE_CONTROL);
+	if (!(val & MSI_CAP_MSI_EN_MASK))
 		return -EINVAL;
 
+	val = (val & MSI_CAP_MME_MASK) >> MSI_CAP_MME_SHIFT;
 	return val;
 }
 

@@ -101,6 +101,7 @@
 #define MSI_MESSAGE_CONTROL		0x52
 #define MSI_CAP_MMC_SHIFT		1
 #define MSI_CAP_MME_SHIFT		4
+#define MSI_CAP_MSI_EN_MASK		0x1
 #define MSI_CAP_MME_MASK		(7 << MSI_CAP_MME_SHIFT)
 #define MSI_MESSAGE_ADDR_L32		0x54
 #define MSI_MESSAGE_ADDR_U32		0x58

Patches currently in stable-queue which might be from [email protected] are

queue-4.15/pci-endpoint-fix-find_first_zero_bit-usage.patch queue-4.15/pci-designware-ep-fix-get_msi-to-check-msi_en-bit.patch