Re: [PATCH v2 1/3] PCI/AER: Fix incorrect return from aer_hest_parse()

[Bjorn Helgaas <bhelgaas@google.com>]

On Thu, May 30, 2013 at 08:39:27AM -0600, Betty Dall wrote:
> The function aer_hest_parse() is called to determine if the given
> PCI device is firmware first or not. The code loops through each
> section of the HEST table to look for a match. The bug is that
> the function always returns whether the last HEST section is firmware
> first. The fix stops the iteration once the info.firmware_first
> variable is set.  This is similar to how the function aer_hest_parse_aff()
> stops the iteration.
> 
> Signed-off-by: Betty Dall <betty.dall@hp.com>
> ---
> 
>  drivers/pci/pcie/aer/aerdrv_acpi.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> 
> diff --git a/drivers/pci/pcie/aer/aerdrv_acpi.c b/drivers/pci/pcie/aer/aerdrv_acpi.c
> index 5194a7d..39b8671 100644
> --- a/drivers/pci/pcie/aer/aerdrv_acpi.c
> +++ b/drivers/pci/pcie/aer/aerdrv_acpi.c
> @@ -42,6 +42,9 @@ static int aer_hest_parse(struct acpi_hest_header *hest_hdr, void *data)
>  	u8 bridge = 0;
>  	int ff = 0;
>  
> +	if (info->firmware_first)
> +		return 0;
> +
>  	switch (hest_hdr->type) {
>  	case ACPI_HEST_TYPE_AER_ROOT_PORT:
>  		pcie_type = PCI_EXP_TYPE_ROOT_PORT;


1) I think dev->__aer_firmware_first should be initialized somewhere in the
pci_scan_single_device() path, e.g., maybe pci_init_capabilities().  It's
known at device add-time and never changes, so there's no point in doing
the lazy setup we do now.  That would let us get rid of
__aer_firmware_first_valid, too (along with the pointless "__" prefix).
This is just an observation, not a requirement for this patch set.

2) This is a band-aid that covers up the real problem, which is that we
update info->firmware_first even for non-matching devices.  I think we
should do something like the following instead:


commit c67612f272f1792a08f012f1b5ca37d5cfde5de4
Author: Bjorn Helgaas <bhelgaas@google.com>
Date:   Mon Jun 3 16:49:12 2013 -0600

    PCI/AER: Don't parse HEST table for non-PCIe devices
    
    AER is a PCIe-only capability, so there's no point in trying to match
    a HEST PCIe structure with a non-PCIe device.
    
    Previously, a HEST global AER bridge entry (type 8) could incorrectly
    match *any* bridge, even a legacy PCI-PCI bridge, and a non-global
    HEST entry could match a legacy PCI device.
    
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/pcie/aer/aerdrv_acpi.c b/drivers/pci/pcie/aer/aerdrv_acpi.c
index 5194a7d..4f798ab 100644
--- a/drivers/pci/pcie/aer/aerdrv_acpi.c
+++ b/drivers/pci/pcie/aer/aerdrv_acpi.c
@@ -59,8 +59,7 @@ static int aer_hest_parse(struct acpi_hest_header *hest_hdr, void *data)
 
 	p = (struct acpi_hest_aer_common *)(hest_hdr + 1);
 	if (p->flags & ACPI_HEST_GLOBAL) {
-		if ((pci_is_pcie(info->pci_dev) &&
-		     pci_pcie_type(info->pci_dev) == pcie_type) || bridge)
+		if ((pci_pcie_type(info->pci_dev) == pcie_type) || bridge)
 			ff = !!(p->flags & ACPI_HEST_FIRMWARE_FIRST);
 	} else
 		if (hest_match_pci(p, info->pci_dev))
@@ -89,6 +88,9 @@ static void aer_set_firmware_first(struct pci_dev *pci_dev)
 
 int pcie_aer_get_firmware_first(struct pci_dev *dev)
 {
+	if (!pci_is_pcie(dev))
+		return 0;
+
 	if (!dev->__aer_firmware_first_valid)
 		aer_set_firmware_first(dev);
 	return dev->__aer_firmware_first;

commit 947da50270686b0d70f4bc2f7323ef7229489ecb
Author: Bjorn Helgaas <bhelgaas@google.com>
Date:   Mon Jun 3 15:42:00 2013 -0600

    PCI/AER: Factor out HEST device type matching
    
    This factors out the matching of HEST structure type and PCIe device type
    to improve readability.  No functional change.
    
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/pcie/aer/aerdrv_acpi.c b/drivers/pci/pcie/aer/aerdrv_acpi.c
index 4f798ab..56e2d94 100644
--- a/drivers/pci/pcie/aer/aerdrv_acpi.c
+++ b/drivers/pci/pcie/aer/aerdrv_acpi.c
@@ -29,6 +29,22 @@ static inline int hest_match_pci(struct acpi_hest_aer_common *p,
 		 p->function == PCI_FUNC(pci->devfn));
 }
 
+static inline bool hest_match_type(struct acpi_hest_header *hest_hdr,
+				   struct pci_dev *dev)
+{
+	u16 hest_type = hest_hdr->type;
+	u8 pcie_type = pci_pcie_type(dev);
+
+	if ((hest_type == ACPI_HEST_TYPE_AER_ROOT_PORT &&
+	     pcie_type == PCI_EXP_TYPE_ROOT_PORT) ||
+	    (hest_type == ACPI_HEST_TYPE_AER_ENDPOINT &&
+	     pcie_type == PCI_EXP_TYPE_ENDPOINT) ||
+	    (hest_type == ACPI_HEST_TYPE_AER_BRIDGE &&
+	     (dev->class >> 16) == PCI_BASE_CLASS_BRIDGE))
+		return true;
+	return false;
+}
+
 struct aer_hest_parse_info {
 	struct pci_dev *pci_dev;
 	int firmware_first;
@@ -38,28 +54,11 @@ static int aer_hest_parse(struct acpi_hest_header *hest_hdr, void *data)
 {
 	struct aer_hest_parse_info *info = data;
 	struct acpi_hest_aer_common *p;
-	u8 pcie_type = 0;
-	u8 bridge = 0;
 	int ff = 0;
 
-	switch (hest_hdr->type) {
-	case ACPI_HEST_TYPE_AER_ROOT_PORT:
-		pcie_type = PCI_EXP_TYPE_ROOT_PORT;
-		break;
-	case ACPI_HEST_TYPE_AER_ENDPOINT:
-		pcie_type = PCI_EXP_TYPE_ENDPOINT;
-		break;
-	case ACPI_HEST_TYPE_AER_BRIDGE:
-		if ((info->pci_dev->class >> 16) == PCI_BASE_CLASS_BRIDGE)
-			bridge = 1;
-		break;
-	default:
-		return 0;
-	}
-
 	p = (struct acpi_hest_aer_common *)(hest_hdr + 1);
 	if (p->flags & ACPI_HEST_GLOBAL) {
-		if ((pci_pcie_type(info->pci_dev) == pcie_type) || bridge)
+		if (hest_match_type(hest_hdr, info->pci_dev))
 			ff = !!(p->flags & ACPI_HEST_FIRMWARE_FIRST);
 	} else
 		if (hest_match_pci(p, info->pci_dev))

commit e9f977a04d96a54c4f6aa0b831e725dab2154364
Author: Bjorn Helgaas <bhelgaas@google.com>
Date:   Mon Jun 3 19:47:27 2013 -0600

    PCI/AER: Set dev->__aer_firmware_first only for matching devices
    
    Previously, we always updated info->firmware_first, even for HEST entries
    that didn't match the device.  Therefore, if the last HEST descriptor was
    a PCIe structure that didn't match the device, we always cleared
    dev->__aer_firmware_first.
    
    Based-on-patch-by: Betty Dall <betty.dall@hp.com>
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/pcie/aer/aerdrv_acpi.c b/drivers/pci/pcie/aer/aerdrv_acpi.c
index 56e2d94..2bedad8 100644
--- a/drivers/pci/pcie/aer/aerdrv_acpi.c
+++ b/drivers/pci/pcie/aer/aerdrv_acpi.c
@@ -54,16 +54,16 @@ static int aer_hest_parse(struct acpi_hest_header *hest_hdr, void *data)
 {
 	struct aer_hest_parse_info *info = data;
 	struct acpi_hest_aer_common *p;
-	int ff = 0;
+	int ff;
 
 	p = (struct acpi_hest_aer_common *)(hest_hdr + 1);
-	if (p->flags & ACPI_HEST_GLOBAL) {
+	ff = !!(p->flags & ACPI_HEST_FIRMWARE_FIRST);
+	if (p->flags & ACPI_HEST_GLOBAL)
 		if (hest_match_type(hest_hdr, info->pci_dev))
-			ff = !!(p->flags & ACPI_HEST_FIRMWARE_FIRST);
-	} else
+			info->firmware_first = ff;
+	else
 		if (hest_match_pci(p, info->pci_dev))
-			ff = !!(p->flags & ACPI_HEST_FIRMWARE_FIRST);
-	info->firmware_first = ff;
+			info->firmware_first = ff;
 
 	return 0;
 }