[PATCH 3/3] PCI: Handle TLP Log in Flit mode

From: Ilpo Järvinen
Date: Fri Jun 14 2024 - 11:19:02 EST

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In reply to: Ilpo Järvinen: "[PATCH 2/3] PCI: Track Flit Mode Status & print it with link status"
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Flit mode introduced in PCIe r6.0 alters how the TLP Header Log is
presented through AER and DPC Capability registers. The TLP Prefix Log
Register is not present with Flit mode and the register becomes
extension for TLP Header Log (PCIe r6.1 secs 7.8.4.12 & 7.9.14.13).

Adapt pcie_read_tlp_log() and struct pcie_tlp_log to read and store
also the extended TLP Header Log when the link is in Flit mode. As
Prefix Log and Extended TLP Header are not present at the same time,
C union can be used.

Determining whether the error occurred while the Link was in Flit mode
is bit complicated. In case of AER, Advanced Error Capabilities and
Control Register directly tells whether the error was logged in Flit
mode or not (PCIe r6.1 sec 7.8.4.7). DPC Capability (PCIe r6.1 sec
7.9.14), unfortunately, does not contain the same information.

Unlike AER, the DPC capability does not provide way to discern whether
the error was logged in Flit mode (this is confirmed by PCI WG to be an
oversight in the spec). DPC will bring link down immediately following
an error, which make it impossible to acquire the Flit mode status
directly from the Link Status 2 register because Flit Mode Status is
only set in certain Link states (PCIe r6.1 sec 7.5.3.20). As a
workaround, use the flit_mode value stored into the struct pci_bus.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
---
drivers/pci/pci.h | 5 +--
drivers/pci/pcie/aer.c | 4 ++-
drivers/pci/pcie/dpc.c | 23 +++++++++++---
drivers/pci/pcie/tlp.c | 57 ++++++++++++++++++++++++-----------
include/linux/aer.h | 13 ++++++--
include/ras/ras_event.h | 12 ++++----
include/uapi/linux/pci_regs.h | 6 +++-
7 files changed, 85 insertions(+), 35 deletions(-)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 54f5a1584ed8..12e8cfd04ebe 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -425,8 +425,9 @@ int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info);
void aer_print_error(struct pci_dev *dev, struct aer_err_info *info);

int pcie_read_tlp_log(struct pci_dev *dev, int where, int where2,
- unsigned int tlp_len, struct pcie_tlp_log *log);
-unsigned int aer_tlp_log_len(struct pci_dev *dev);
+ unsigned int tlp_len, bool flit,
+ struct pcie_tlp_log *log);
+unsigned int aer_tlp_log_len(struct pci_dev *dev, u32 aercc);
void pcie_print_tlp_log(const struct pci_dev *dev,
const struct pcie_tlp_log *log, const char *pfx);
#endif /* CONFIG_PCIEAER */
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index efb9e728fe94..6beb856964e1 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -1241,7 +1241,9 @@ int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info)
info->tlp_header_valid = 1;
pcie_read_tlp_log(dev, aer + PCI_ERR_HEADER_LOG,
aer + PCI_ERR_PREFIX_LOG,
- aer_tlp_log_len(dev), &info->tlp);
+ aer_tlp_log_len(dev, aercc),
+ aercc & PCI_ERR_CAP_TLP_LOG_FLIT,
+ &info->tlp);
}
}

diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
index 598f74384471..a374f3216ce2 100644
--- a/drivers/pci/pcie/dpc.c
+++ b/drivers/pci/pcie/dpc.c
@@ -219,7 +219,9 @@ static void dpc_process_rp_pio_error(struct pci_dev *pdev)
goto clear_status;
pcie_read_tlp_log(pdev, cap + PCI_EXP_DPC_RP_PIO_HEADER_LOG,
cap + PCI_EXP_DPC_RP_PIO_TLPPREFIX_LOG,
- dpc_tlp_log_len(pdev), &tlp_log);
+ dpc_tlp_log_len(pdev),
+ pdev->subordinate->flit_mode,
+ &tlp_log);
pcie_print_tlp_log(pdev, &tlp_log, "");

if (pdev->dpc_rp_log_size < 5)
@@ -398,12 +400,23 @@ void pci_dpc_init(struct pci_dev *pdev)

/* Quirks may set dpc_rp_log_size if device or firmware is buggy */
if (!pdev->dpc_rp_log_size) {
+ u16 flags;
+ int ret;
+
+ ret = pcie_capability_read_word(pdev, PCI_EXP_FLAGS, &flags);
+ if (ret)
+ return;
+
pdev->dpc_rp_log_size =
FIELD_GET(PCI_EXP_DPC_RP_PIO_LOG_SIZE, cap);
- if (pdev->dpc_rp_log_size < 4 || pdev->dpc_rp_log_size > 9) {
- pci_err(pdev, "RP PIO log size %u is invalid\n",
- pdev->dpc_rp_log_size);
- pdev->dpc_rp_log_size = 0;
+ if (FIELD_GET(PCI_EXP_FLAGS_FLIT, flags)) {
+ pdev->dpc_rp_log_size += FIELD_GET(PCI_EXP_DPC_RP_PIO_LOG_SIZE4, cap) << 4;
+ } else {
+ if (pdev->dpc_rp_log_size < 4 || pdev->dpc_rp_log_size > 9) {
+ pci_err(pdev, "RP PIO log size %u is invalid\n",
+ pdev->dpc_rp_log_size);
+ pdev->dpc_rp_log_size = 0;
+ }
}
}
}
diff --git a/drivers/pci/pcie/tlp.c b/drivers/pci/pcie/tlp.c
index 097ac8514e96..5e68b1516f68 100644
--- a/drivers/pci/pcie/tlp.c
+++ b/drivers/pci/pcie/tlp.c
@@ -7,6 +7,7 @@

#include <linux/aer.h>
#include <linux/array_size.h>
+#include <linux/bitfield.h>
#include <linux/pci.h>
#include <linux/string.h>

@@ -15,11 +16,15 @@
/**
* aer_tlp_log_len - Calculates AER Capability TLP Header/Prefix Log length
* @dev: PCIe device
+ * @aercc: AER Capabilities and Control register value
*
* Return: TLP Header/Prefix Log length
*/
-unsigned int aer_tlp_log_len(struct pci_dev *dev)
+unsigned int aer_tlp_log_len(struct pci_dev *dev, u32 aercc)
{
+ if (aercc & PCI_ERR_CAP_TLP_LOG_FLIT)
+ return FIELD_GET(PCI_ERR_CAP_TLP_LOG_SIZE, aercc);
+
return 4 + dev->eetlp_prefix_max;
}

@@ -46,6 +51,7 @@ unsigned int dpc_tlp_log_len(struct pci_dev *dev)
* @where: PCI Config offset of TLP Header Log
* @where2: PCI Config offset of TLP Prefix Log
* @tlp_len: TLP Log length (Header Log + TLP Prefix Log in DWORDs)
+ * @flit: TLP Logged in Flit mode
* @log: TLP Log structure to fill
*
* Fill @log from TLP Header Log registers, e.g., AER or DPC.
@@ -53,28 +59,34 @@ unsigned int dpc_tlp_log_len(struct pci_dev *dev)
* Return: 0 on success and filled TLP Log structure, <0 on error.
*/
int pcie_read_tlp_log(struct pci_dev *dev, int where, int where2,
- unsigned int tlp_len, struct pcie_tlp_log *log)
+ unsigned int tlp_len, bool flit, struct pcie_tlp_log *log)
{
unsigned int i;
int off, ret;
- u32 *to;
+
+ if (tlp_len > ARRAY_SIZE(log->dw))
+ tlp_len = ARRAY_SIZE(log->dw);

memset(log, 0, sizeof(*log));

for (i = 0; i < tlp_len; i++) {
- if (i < 4) {
+ if (i < 4)
off = where + i * 4;
- to = &log->dw[i];
- } else {
+ else
off = where2 + (i - 4) * 4;
- to = &log->prefix[i - 4];
- }

- ret = pci_read_config_dword(dev, off, to);
+ ret = pci_read_config_dword(dev, off, &log->dw[i]);
if (ret)
return pcibios_err_to_errno(ret);
}

+ /*
+ * Hard-code non-Flit mode to 4 DWORDs, for now. The exact length
+ * can only be known if the TLP is parsed.
+ */
+ log->header_len = flit ? tlp_len : 4;
+ log->flit = flit;
+
return 0;
}

@@ -89,21 +101,30 @@ int pcie_read_tlp_log(struct pci_dev *dev, int where, int where2,
void pcie_print_tlp_log(const struct pci_dev *dev,
const struct pcie_tlp_log *log, const char *pfx)
{
- char buf[(10 + 1) * (4 + ARRAY_SIZE(log->prefix)) + 14 + 1];
+ char buf[(10 + 1) * PCIE_TLP_LOG_MAXLEN + 1];
unsigned int i;
int len;

len = scnprintf(buf, sizeof(buf), "%#010x %#010x %#010x %#010x",
log->dw[0], log->dw[1], log->dw[2], log->dw[3]);

- if (log->prefix[0])
- len += scnprintf(buf + len, sizeof(buf) - len, " E-E Prefixes:");
- for (i = 0; i < ARRAY_SIZE(log->prefix); i++) {
- if (!log->prefix[i])
- break;
- len += scnprintf(buf + len, sizeof(buf) - len,
- " %#010x", log->prefix[i]);
+ if (log->flit) {
+ for (i = 4; i < log->header_len; i++) {
+ len += scnprintf(buf + len, sizeof(buf) - len,
+ " %#010x", log->dw[i]);
+ }
+ } else {
+ if (log->prefix[0])
+ len += scnprintf(buf + len, sizeof(buf) - len,
+ " E-E Prefixes:");
+ for (i = 0; i < ARRAY_SIZE(log->prefix); i++) {
+ if (!log->prefix[i])
+ break;
+ len += scnprintf(buf + len, sizeof(buf) - len,
+ " %#010x", log->prefix[i]);
+ }
}

- pci_err(dev, "%sTLP Header: %s\n", pfx, buf);
+ pci_err(dev, "%sTLP Header%s: %s\n", pfx,
+ log->flit ? " (Flit)" : "", buf);
}
diff --git a/include/linux/aer.h b/include/linux/aer.h
index dc498adaa1c8..96d1f83e4a65 100644
--- a/include/linux/aer.h
+++ b/include/linux/aer.h
@@ -18,9 +18,18 @@

struct pci_dev;

+#define PCIE_TLP_LOG_MAXLEN 14
+
struct pcie_tlp_log {
- u32 dw[4];
- u32 prefix[4];
+ union {
+ u32 dw[PCIE_TLP_LOG_MAXLEN];
+ struct {
+ u32 _do_not_use[4];
+ u32 prefix[4];
+ };
+ };
+ u8 header_len; /* Length of the Logged TLP Header in DWORDs */
+ bool flit; /* TLP was logged when in Flit mode */
};

struct aer_capability_regs {
diff --git a/include/ras/ras_event.h b/include/ras/ras_event.h
index 7c47151d5c72..316d216e0573 100644
--- a/include/ras/ras_event.h
+++ b/include/ras/ras_event.h
@@ -309,7 +309,7 @@ TRACE_EVENT(aer_event,
__field( u32, status )
__field( u8, severity )
__field( u8, tlp_header_valid)
- __array( u32, tlp_header, 4 )
+ __array( u32, tlp_header, PCIE_TLP_LOG_MAXLEN )
),

TP_fast_assign(
@@ -318,10 +318,10 @@ TRACE_EVENT(aer_event,
__entry->severity = severity;
__entry->tlp_header_valid = tlp_header_valid;
if (tlp_header_valid) {
- __entry->tlp_header[0] = tlp->dw[0];
- __entry->tlp_header[1] = tlp->dw[1];
- __entry->tlp_header[2] = tlp->dw[2];
- __entry->tlp_header[3] = tlp->dw[3];
+ int i;
+
+ for (i = 0; i < PCIE_TLP_LOG_MAXLEN; i++)
+ __entry->tlp_header[i] = tlp->dw[i];
}
),

@@ -334,7 +334,7 @@ TRACE_EVENT(aer_event,
__print_flags(__entry->status, "|", aer_correctable_errors) :
__print_flags(__entry->status, "|", aer_uncorrectable_errors),
__entry->tlp_header_valid ?
- __print_array(__entry->tlp_header, 4, 4) :
+ __print_array(__entry->tlp_header, PCIE_TLP_LOG_MAXLEN, 4) :
"Not available")
);

diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index b6f9012a3fc4..161b67525447 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -485,6 +485,7 @@
#define PCI_EXP_TYPE_RC_EC 0xa /* Root Complex Event Collector */
#define PCI_EXP_FLAGS_SLOT 0x0100 /* Slot implemented */
#define PCI_EXP_FLAGS_IRQ 0x3e00 /* Interrupt message number */
+#define PCI_EXP_FLAGS_FLIT 0x8000 /* Flit Mode Supported */
#define PCI_EXP_DEVCAP 0x04 /* Device capabilities */
#define PCI_EXP_DEVCAP_PAYLOAD 0x00000007 /* Max_Payload_Size */
#define PCI_EXP_DEVCAP_PHANTOM 0x00000018 /* Phantom functions */
@@ -788,6 +789,8 @@
#define PCI_ERR_CAP_ECRC_GENE 0x00000040 /* ECRC Generation Enable */
#define PCI_ERR_CAP_ECRC_CHKC 0x00000080 /* ECRC Check Capable */
#define PCI_ERR_CAP_ECRC_CHKE 0x00000100 /* ECRC Check Enable */
+#define PCI_ERR_CAP_TLP_LOG_FLIT 0x00040000 /* TLP was logged in Flit Mode */
+#define PCI_ERR_CAP_TLP_LOG_SIZE 0x00f80000 /* Logged TLP Size (only in Flit mode) */
#define PCI_ERR_HEADER_LOG 0x1c /* Header Log Register (16 bytes) */
#define PCI_ERR_ROOT_COMMAND 0x2c /* Root Error Command */
#define PCI_ERR_ROOT_CMD_COR_EN 0x00000001 /* Correctable Err Reporting Enable */
@@ -1038,8 +1041,9 @@
#define PCI_EXP_DPC_CAP_RP_EXT 0x0020 /* Root Port Extensions */
#define PCI_EXP_DPC_CAP_POISONED_TLP 0x0040 /* Poisoned TLP Egress Blocking Supported */
#define PCI_EXP_DPC_CAP_SW_TRIGGER 0x0080 /* Software Triggering Supported */
-#define PCI_EXP_DPC_RP_PIO_LOG_SIZE 0x0F00 /* RP PIO Log Size */
+#define PCI_EXP_DPC_RP_PIO_LOG_SIZE 0x0F00 /* RP PIO Log Size [3:0] */
#define PCI_EXP_DPC_CAP_DL_ACTIVE 0x1000 /* ERR_COR signal on DL_Active supported */
+#define PCI_EXP_DPC_RP_PIO_LOG_SIZE4 0x2000 /* RP PIO Log Size [4] */

#define PCI_EXP_DPC_CTL 0x06 /* DPC control */
#define PCI_EXP_DPC_CTL_EN_FATAL 0x0001 /* Enable trigger on ERR_FATAL message */
--
2.39.2

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In reply to: Ilpo Järvinen: "[PATCH 2/3] PCI: Track Flit Mode Status & print it with link status"
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