Re: [PATCH v15 3/5] PCI/EDR: Export AER, DPC and error recovery functions

[Bjorn Helgaas <helgaas@kernel.org>]

On Wed, Feb 26, 2020 at 11:30:43AM -0800, Kuppuswamy Sathyanarayanan wrote:
> On 2/25/20 5:02 PM, Bjorn Helgaas wrote:
> > On Thu, Feb 13, 2020 at 10:20:15AM -0800, sathyanarayanan.kuppuswamy@linux.intel.com wrote:
> > > From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> > > ...

> > > +int pci_cleanup_aer_error_status_regs(struct pci_dev *dev)
> > > +{
> > > +	if (pcie_aer_get_firmware_first(dev))
> > > +		return -EIO;
> > > +
> > > +	return pci_aer_clear_err_status_regs(dev);
> > > +}
> > We started with these:
> > 
> >    pci_cleanup_aer_uncorrect_error_status()
> >    pci_aer_clear_fatal_status()
> >    pci_cleanup_aer_error_status_regs()
> > 
> > This was already a mess.  They do basically similar things, but the
> > function names are a complete jumble.  Let's start with preliminary
> > patches to name them consistently, e.g.,
> > 
> >    pci_aer_clear_nonfatal_status()
> >    pci_aer_clear_fatal_status()
> >    pci_aer_clear_status()
> > 
> > Now, for EDR you eventually add this in edr_handle_event():
> > 
> >    edr_handle_event()
> >    {
> >      ...
> >      pci_aer_clear_err_uncor_status(pdev);
> >      pci_aer_clear_err_fatal_status(pdev);
> >      pci_aer_clear_err_status_regs(pdev);
> > 
> > I see that this path needs to clear the status even in the
> > firmware-first case, so you do need some change for that.  But
> > pci_aer_clear_err_status_regs() does exactly the same thing as
> > pci_aer_clear_err_uncor_status() and pci_aer_clear_err_fatal_status()
> > plus a little more (clearing PCI_ERR_ROOT_STATUS), so it should be
> > sufficient to just call pci_aer_clear_err_status_regs().
> > 
> > So I don't think you need to make wrappers for
> > pci_aer_clear_nonfatal_status() and pci_aer_clear_fatal_status() at
> > all since they're not needed by the EDR path.
> > 
> > You *do* need a wrapper for pci_aer_clear_status(), but instead of
> > just adding random words ("err", "regs") to the name, please name it
> > something like pci_aer_raw_clear_status() as a hint that it skips
> > some sort of check.

What do you think about the above?

> > I would split this into a separate patch.  This patch contains a bunch
> > of things that aren't really related except that they're needed for
> > EDR.  I think it will be more readable if each patch just does one
> > piece of it.
>
> Ok. I will split it into multiple patches. I just grouped them together
> as a preparatory patch for adding EDR support.

Sounds good.

> > > diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> > > index 99fca8400956..acae12dbf9ff 100644
> > > --- a/drivers/pci/pcie/dpc.c
> > > +++ b/drivers/pci/pcie/dpc.c
> > > @@ -15,15 +15,9 @@
> > >   #include <linux/pci.h>
> > >   #include "portdrv.h"
> > > +#include "dpc.h"
> > >   #include "../pci.h"
> > > -struct dpc_dev {
> > > -	struct pci_dev		*pdev;
> > > -	u16			cap_pos;
> > > -	bool			rp_extensions;
> > > -	u8			rp_log_size;
> > > -};

> > Adding dpc.h shouldn't be in this patch because there's no need for a
> > separate dpc.h file yet -- it's only included this one place.  I'm not
> > positive a dpc.h is needed at all -- see comments on patch [4/5].

> Yes, if we use pdev in dpc functions used by EDR code, we should
> not need it.

I think struct dpc_dev might be more trouble than it's worth.  I
attached a possible patch at the end that folds the 25 bits of
DPC-related info into the struct pci_dev and gets rid of struct
dpc_dev completely.  I compiled it but haven't tested it.

> > > -static pci_ers_result_t dpc_reset_link(struct pci_dev *pdev)
> > > +pci_ers_result_t dpc_reset_link_common(struct dpc_dev *dpc)
> > >   {
> > I don't see why you need to split this into dpc_reset_link_common()
> > and dpc_reset_link().  IIUC, you split it so the DPC driver path can
> > supply a pci_dev * via
> > 
> >    dpc_handler
> >      pcie_do_recovery
> >        pcie_do_recovery_common(..., NULL, NULL)
> >          reset_link(..., NULL, NULL)
> >            driver->reset_link(pdev)
> >              dpc_reset_link(pdev)
> >                dpc = to_dpc_dev(pdev)
>
> I have split it mainly because of dpc_dev dependency. If we use
> dpc_reset_link(pdev) directly it will try to find related dpc_dev using
> to_dpc_dev() function. But this will not work in FF mode where DPC
> is handled by firmware and hence we will not have DPC pcie_port
> service driver enumerated for this device.

The patch below might help this case.

> > > +void dpc_dev_init(struct pci_dev *pdev, struct dpc_dev *dpc)
> > > +{
> > Can you include the kzalloc() here so we don't have to do the alloc in
> > pci_acpi_add_edr_notifier()?

> Currently dpc driver allocates dpc_dev structure using pcie_port->device
> reference in its devm_alloc* calls. But if we allocate dpc_dev inside
> this function we should use pci_dev->dev reference for it. Is it OK to us
> pci_dev->dev reference for DPC driver allocations ?

I think the patch below would solve this issue too because we don't
need the alloc at all.

> > I think there's also a leak there: pci_acpi_add_edr_notifier()
> > kzallocs a struct dpc_dev, but I don't see a corresponding kfree().

> since we are using devm_allocs, It should be freed when removing
> the PCI device right?

Oh, right, sorry.


commit 7fb9f4495711 ("PCI/DPC: Move data to struct pci_dev")
Author: Bjorn Helgaas <bhelgaas@google.com>
Date:   Wed Feb 26 08:00:55 2020 -0600

    PCI/DPC: Move data to struct pci_dev
    

diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
index e06f42f58d3d..6b116d7fdb89 100644
--- a/drivers/pci/pcie/dpc.c
+++ b/drivers/pci/pcie/dpc.c
@@ -17,13 +17,6 @@
 #include "portdrv.h"
 #include "../pci.h"
 
-struct dpc_dev {
-	struct pcie_device	*dev;
-	u16			cap_pos;
-	bool			rp_extensions;
-	u8			rp_log_size;
-};
-
 static const char * const rp_pio_error_string[] = {
 	"Configuration Request received UR Completion",	 /* Bit Position 0  */
 	"Configuration Request received CA Completion",	 /* Bit Position 1  */
@@ -46,63 +39,42 @@ static const char * const rp_pio_error_string[] = {
 	"Memory Request Completion Timeout",		 /* Bit Position 18 */
 };
 
-static struct dpc_dev *to_dpc_dev(struct pci_dev *dev)
-{
-	struct device *device;
-
-	device = pcie_port_find_device(dev, PCIE_PORT_SERVICE_DPC);
-	if (!device)
-		return NULL;
-	return get_service_data(to_pcie_device(device));
-}
-
 void pci_save_dpc_state(struct pci_dev *dev)
 {
-	struct dpc_dev *dpc;
 	struct pci_cap_saved_state *save_state;
 	u16 *cap;
 
 	if (!pci_is_pcie(dev))
 		return;
 
-	dpc = to_dpc_dev(dev);
-	if (!dpc)
-		return;
-
 	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_DPC);
 	if (!save_state)
 		return;
 
 	cap = (u16 *)&save_state->cap.data[0];
-	pci_read_config_word(dev, dpc->cap_pos + PCI_EXP_DPC_CTL, cap);
+	pci_read_config_word(dev, dev->dpc_cap + PCI_EXP_DPC_CTL, cap);
 }
 
 void pci_restore_dpc_state(struct pci_dev *dev)
 {
-	struct dpc_dev *dpc;
 	struct pci_cap_saved_state *save_state;
 	u16 *cap;
 
 	if (!pci_is_pcie(dev))
 		return;
 
-	dpc = to_dpc_dev(dev);
-	if (!dpc)
-		return;
-
 	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_DPC);
 	if (!save_state)
 		return;
 
 	cap = (u16 *)&save_state->cap.data[0];
-	pci_write_config_word(dev, dpc->cap_pos + PCI_EXP_DPC_CTL, *cap);
+	pci_write_config_word(dev, dev->dpc_cap + PCI_EXP_DPC_CTL, *cap);
 }
 
-static int dpc_wait_rp_inactive(struct dpc_dev *dpc)
+static int dpc_wait_rp_inactive(struct pci_dev *pdev)
 {
 	unsigned long timeout = jiffies + HZ;
-	struct pci_dev *pdev = dpc->dev->port;
-	u16 cap = dpc->cap_pos, status;
+	u16 cap = pdev->dpc_cap, status;
 
 	pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status);
 	while (status & PCI_EXP_DPC_RP_BUSY &&
@@ -119,15 +91,13 @@ static int dpc_wait_rp_inactive(struct dpc_dev *dpc)
 
 static pci_ers_result_t dpc_reset_link(struct pci_dev *pdev)
 {
-	struct dpc_dev *dpc;
 	u16 cap;
 
 	/*
 	 * DPC disables the Link automatically in hardware, so it has
 	 * already been reset by the time we get here.
 	 */
-	dpc = to_dpc_dev(pdev);
-	cap = dpc->cap_pos;
+	cap = pdev->dpc_cap;
 
 	/*
 	 * Wait until the Link is inactive, then clear DPC Trigger Status
@@ -135,7 +105,7 @@ static pci_ers_result_t dpc_reset_link(struct pci_dev *pdev)
 	 */
 	pcie_wait_for_link(pdev, false);
 
-	if (dpc->rp_extensions && dpc_wait_rp_inactive(dpc))
+	if (pdev->dpc_rp_extensions && dpc_wait_rp_inactive(pdev))
 		return PCI_ERS_RESULT_DISCONNECT;
 
 	pci_write_config_word(pdev, cap + PCI_EXP_DPC_STATUS,
@@ -147,10 +117,9 @@ static pci_ers_result_t dpc_reset_link(struct pci_dev *pdev)
 	return PCI_ERS_RESULT_RECOVERED;
 }
 
-static void dpc_process_rp_pio_error(struct dpc_dev *dpc)
+static void dpc_process_rp_pio_error(struct pci_dev *pdev)
 {
-	struct pci_dev *pdev = dpc->dev->port;
-	u16 cap = dpc->cap_pos, dpc_status, first_error;
+	u16 cap = pdev->dpc_cap, dpc_status, first_error;
 	u32 status, mask, sev, syserr, exc, dw0, dw1, dw2, dw3, log, prefix;
 	int i;
 
@@ -175,7 +144,7 @@ static void dpc_process_rp_pio_error(struct dpc_dev *dpc)
 				first_error == i ? " (First)" : "");
 	}
 
-	if (dpc->rp_log_size < 4)
+	if (pdev->dpc_rp_log_size < 4)
 		goto clear_status;
 	pci_read_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_HEADER_LOG,
 			      &dw0);
@@ -188,12 +157,12 @@ static void dpc_process_rp_pio_error(struct dpc_dev *dpc)
 	pci_err(pdev, "TLP Header: %#010x %#010x %#010x %#010x\n",
 		dw0, dw1, dw2, dw3);
 
-	if (dpc->rp_log_size < 5)
+	if (pdev->dpc_rp_log_size < 5)
 		goto clear_status;
 	pci_read_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_IMPSPEC_LOG, &log);
 	pci_err(pdev, "RP PIO ImpSpec Log %#010x\n", log);
 
-	for (i = 0; i < dpc->rp_log_size - 5; i++) {
+	for (i = 0; i < pdev->dpc_rp_log_size - 5; i++) {
 		pci_read_config_dword(pdev,
 			cap + PCI_EXP_DPC_RP_PIO_TLPPREFIX_LOG, &prefix);
 		pci_err(pdev, "TLP Prefix Header: dw%d, %#010x\n", i, prefix);
@@ -226,10 +195,9 @@ static int dpc_get_aer_uncorrect_severity(struct pci_dev *dev,
 
 static irqreturn_t dpc_handler(int irq, void *context)
 {
+	struct pci_dev *pdev = context;
+	u16 cap = pdev->dpc_cap, status, source, reason, ext_reason;
 	struct aer_err_info info;
-	struct dpc_dev *dpc = context;
-	struct pci_dev *pdev = dpc->dev->port;
-	u16 cap = dpc->cap_pos, status, source, reason, ext_reason;
 
 	pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status);
 	pci_read_config_word(pdev, cap + PCI_EXP_DPC_SOURCE_ID, &source);
@@ -248,8 +216,8 @@ static irqreturn_t dpc_handler(int irq, void *context)
 				     "reserved error");
 
 	/* show RP PIO error detail information */
-	if (dpc->rp_extensions && reason == 3 && ext_reason == 0)
-		dpc_process_rp_pio_error(dpc);
+	if (pdev->dpc_rp_extensions && reason == 3 && ext_reason == 0)
+		dpc_process_rp_pio_error(pdev);
 	else if (reason == 0 &&
 		 dpc_get_aer_uncorrect_severity(pdev, &info) &&
 		 aer_get_device_error_info(pdev, &info)) {
@@ -266,9 +234,8 @@ static irqreturn_t dpc_handler(int irq, void *context)
 
 static irqreturn_t dpc_irq(int irq, void *context)
 {
-	struct dpc_dev *dpc = (struct dpc_dev *)context;
-	struct pci_dev *pdev = dpc->dev->port;
-	u16 cap = dpc->cap_pos, status;
+	struct pci_dev *pdev = context;
+	u16 cap = pdev->dpc_cap, status;
 
 	pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status);
 
@@ -285,7 +252,6 @@ static irqreturn_t dpc_irq(int irq, void *context)
 #define FLAG(x, y) (((x) & (y)) ? '+' : '-')
 static int dpc_probe(struct pcie_device *dev)
 {
-	struct dpc_dev *dpc;
 	struct pci_dev *pdev = dev->port;
 	struct device *device = &dev->device;
 	int status;
@@ -294,43 +260,37 @@ static int dpc_probe(struct pcie_device *dev)
 	if (pcie_aer_get_firmware_first(pdev) && !pcie_ports_dpc_native)
 		return -ENOTSUPP;
 
-	dpc = devm_kzalloc(device, sizeof(*dpc), GFP_KERNEL);
-	if (!dpc)
-		return -ENOMEM;
-
-	dpc->cap_pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_DPC);
-	dpc->dev = dev;
-	set_service_data(dev, dpc);
+	pdev->dpc_cap = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_DPC);
 
 	status = devm_request_threaded_irq(device, dev->irq, dpc_irq,
 					   dpc_handler, IRQF_SHARED,
-					   "pcie-dpc", dpc);
+					   "pcie-dpc", pdev);
 	if (status) {
 		pci_warn(pdev, "request IRQ%d failed: %d\n", dev->irq,
 			 status);
 		return status;
 	}
 
-	pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CAP, &cap);
-	pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl);
+	pci_read_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CAP, &cap);
+	pci_read_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, &ctl);
 
-	dpc->rp_extensions = (cap & PCI_EXP_DPC_CAP_RP_EXT);
-	if (dpc->rp_extensions) {
-		dpc->rp_log_size = (cap & PCI_EXP_DPC_RP_PIO_LOG_SIZE) >> 8;
-		if (dpc->rp_log_size < 4 || dpc->rp_log_size > 9) {
+	pdev->dpc_rp_extensions = (cap & PCI_EXP_DPC_CAP_RP_EXT) ? 1 : 0;
+	if (pdev->dpc_rp_extensions) {
+		pdev->dpc_rp_log_size = (cap & PCI_EXP_DPC_RP_PIO_LOG_SIZE) >> 8;
+		if (pdev->dpc_rp_log_size < 4 || pdev->dpc_rp_log_size > 9) {
 			pci_err(pdev, "RP PIO log size %u is invalid\n",
-				dpc->rp_log_size);
-			dpc->rp_log_size = 0;
+				pdev->dpc_rp_log_size);
+			pdev->dpc_rp_log_size = 0;
 		}
 	}
 
 	ctl = (ctl & 0xfff4) | PCI_EXP_DPC_CTL_EN_FATAL | PCI_EXP_DPC_CTL_INT_EN;
-	pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl);
+	pci_write_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, ctl);
 
 	pci_info(pdev, "error containment capabilities: Int Msg #%d, RPExt%c PoisonedTLP%c SwTrigger%c RP PIO Log %d, DL_ActiveErr%c\n",
 		 cap & PCI_EXP_DPC_IRQ, FLAG(cap, PCI_EXP_DPC_CAP_RP_EXT),
 		 FLAG(cap, PCI_EXP_DPC_CAP_POISONED_TLP),
-		 FLAG(cap, PCI_EXP_DPC_CAP_SW_TRIGGER), dpc->rp_log_size,
+		 FLAG(cap, PCI_EXP_DPC_CAP_SW_TRIGGER), pdev->dpc_rp_log_size,
 		 FLAG(cap, PCI_EXP_DPC_CAP_DL_ACTIVE));
 
 	pci_add_ext_cap_save_buffer(pdev, PCI_EXT_CAP_ID_DPC, sizeof(u16));
@@ -339,13 +299,12 @@ static int dpc_probe(struct pcie_device *dev)
 
 static void dpc_remove(struct pcie_device *dev)
 {
-	struct dpc_dev *dpc = get_service_data(dev);
 	struct pci_dev *pdev = dev->port;
 	u16 ctl;
 
-	pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl);
+	pci_read_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, &ctl);
 	ctl &= ~(PCI_EXP_DPC_CTL_EN_FATAL | PCI_EXP_DPC_CTL_INT_EN);
-	pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl);
+	pci_write_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, ctl);
 }
 
 static struct pcie_port_service_driver dpcdriver = {
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 3840a541a9de..a0b7e7a53741 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -444,6 +444,11 @@ struct pci_dev {
 	const struct attribute_group **msi_irq_groups;
 #endif
 	struct pci_vpd *vpd;
+#ifdef CONFIG_PCIE_DPC
+	u16		dpc_cap;
+	unsigned int	dpc_rp_extensions:1;
+	u8		dpc_rp_log_size;
+#endif
 #ifdef CONFIG_PCI_ATS
 	union {
 		struct pci_sriov	*sriov;		/* PF: SR-IOV info */