linux-kernel - [PATCH 4.15 51/84] PCI: designware-ep: Fix ->get_msi() to check MSI

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Date:   Fri, 23 Mar 2018 10:54:05 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Kishon Vijay Abraham I <kishon@...com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.15 51/84] PCI: designware-ep: Fix ->get_msi() to check MSI_EN bit

4.15-stable review patch.  If anyone has any objections, please let me know.

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

From: Kishon Vijay Abraham I <kishon@...com>


[ 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.

Fixes: f8aed6ec624f ("PCI: dwc: designware: Add EP mode support")
Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/pci/dwc/pcie-designware-ep.c |   12 +++---------
 drivers/pci/dwc/pcie-designware.h    |    1 +
 2 files changed, 4 insertions(+), 9 deletions(-)

--- a/drivers/pci/dwc/pcie-designware-ep.c
+++ b/drivers/pci/dwc/pcie-designware-ep.c
@@ -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;
 }
 
--- a/drivers/pci/dwc/pcie-designware.h
+++ b/drivers/pci/dwc/pcie-designware.h
@@ -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