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The helper disables CXL.cache, performs cache writeback when supported, initiates reset with Memory Clear enabled, waits for completion, and re-enables CXL.cache on exit. Leave the helper unregistered until range validation and reset-scope validation are in place. Signed-off-by: Srirangan Madhavan --- drivers/cxl/core/resource.c | 251 ++++++++++++++++++++++++++++++++++ include/cxl/cxl.h | 7 + include/uapi/linux/pci_regs.h | 14 ++ 3 files changed, 272 insertions(+) diff --git a/drivers/cxl/core/resource.c b/drivers/cxl/core/resource.c index 6d9f8fe14b16..9c1aa0800521 100644 --- a/drivers/cxl/core/resource.c +++ b/drivers/cxl/core/resource.c @@ -8,6 +8,8 @@ #include #include #include +#include +#include #include #include #include @@ -492,3 +494,252 @@ void pci_cxl_hdm_init(struct pci_dev *pdev) if (rc && rc != -ENOTTY && rc != -ENODEV) pci_dbg(pdev, "CXL HDM cache init failed: %d\n", rc); } +/* + * CXL r4.0 sec 9.7.2 defines the reset completion timeout encodings. + * Sec 9.7.3 leaves config-space access behavior undefined for 100 ms after + * initiating CXL Reset, then limits software to CXL Status2 access until + * reset completion, timeout, or error. + */ +#define CXL_RESET_RRS_WAIT_MS 100 +#define CXL_RESET_STATUS_POLL_MS 20 +static const u32 cxl_reset_timeout_ms[] = { + 10, 100, 1000, 10000, 100000, +}; + +#define CXL_CACHE_WBI_TIMEOUT_US 100000 +#define CXL_CACHE_WBI_POLL_US 100 + +static int cxl_reset_get_dvsec(struct pci_dev *pdev, u16 *cap_out) +{ + int dvsec, rc; + u16 cap, ctrl; + + dvsec = cxl_pci_get_device_dvsec_cap(pdev, 0, &cap); + if (dvsec < 0) + return dvsec; + + if (!(cap & PCI_DVSEC_CXL_CACHE_CAPABLE) || + !(cap & PCI_DVSEC_CXL_MEM_CAPABLE)) + return -ENOTTY; + + if (!(cap & PCI_DVSEC_CXL_RST_CAPABLE)) + return -ENOTTY; + if (!(cap & PCI_DVSEC_CXL_RST_MEM_CLR_CAPABLE)) + return -ENOTTY; + + rc = pci_read_config_word(pdev, dvsec + PCI_DVSEC_CXL_CTRL, &ctrl); + if (rc) + return pcibios_err_to_errno(rc); + + if (!(ctrl & PCI_DVSEC_CXL_CACHE_ENABLE) || + !(ctrl & PCI_DVSEC_CXL_MEM_ENABLE)) + return -ENOTTY; + + *cap_out = cap; + return dvsec; +} + +#define CXL_RESET_CTRL2_CMD_MASK \ + (PCI_DVSEC_CXL_INIT_CACHE_WBI | PCI_DVSEC_CXL_INIT_CXL_RST) + +static int cxl_reset_read_ctrl2(struct pci_dev *pdev, int dvsec, u16 *ctrl2) +{ + int rc; + + rc = pci_read_config_word(pdev, dvsec + PCI_DVSEC_CXL_CTRL2, ctrl2); + if (rc) + return pcibios_err_to_errno(rc); + + *ctrl2 &= ~CXL_RESET_CTRL2_CMD_MASK; + return 0; +} + +static int cxl_reset_write_ctrl2(struct pci_dev *pdev, int dvsec, u16 ctrl2) +{ + int rc; + + rc = pci_write_config_word(pdev, dvsec + PCI_DVSEC_CXL_CTRL2, ctrl2); + if (rc) + return pcibios_err_to_errno(rc); + + return 0; +} + +static int cxl_reset_modify_ctrl2(struct pci_dev *pdev, int dvsec, u16 set, + u16 clear) +{ + u16 ctrl2; + int rc; + + rc = cxl_reset_read_ctrl2(pdev, dvsec, &ctrl2); + if (rc) + return rc; + + ctrl2 &= ~clear; + ctrl2 |= set; + return cxl_reset_write_ctrl2(pdev, dvsec, ctrl2); +} + +static int cxl_reset_enable_cache(struct pci_dev *pdev, int dvsec) +{ + return cxl_reset_modify_ctrl2(pdev, dvsec, 0, + PCI_DVSEC_CXL_DISABLE_CACHING); +} + +static int cxl_reset_initiate(struct pci_dev *pdev, int dvsec) +{ + return cxl_reset_modify_ctrl2(pdev, dvsec, + PCI_DVSEC_CXL_INIT_CXL_RST | + PCI_DVSEC_CXL_RST_MEM_CLR_EN, 0); +} + +static int cxl_reset_wait_cache_wbi(struct pci_dev *pdev, int dvsec) +{ + unsigned long deadline; + u16 status2; + int rc; + + rc = cxl_reset_modify_ctrl2(pdev, dvsec, + PCI_DVSEC_CXL_INIT_CACHE_WBI, 0); + if (rc) + return rc; + + deadline = jiffies + usecs_to_jiffies(CXL_CACHE_WBI_TIMEOUT_US); + do { + usleep_range(CXL_CACHE_WBI_POLL_US, CXL_CACHE_WBI_POLL_US + 1); + + rc = pci_read_config_word(pdev, dvsec + PCI_DVSEC_CXL_STATUS2, + &status2); + if (rc) + return pcibios_err_to_errno(rc); + if (status2 != U16_MAX && (status2 & PCI_DVSEC_CXL_CACHE_INV)) + return 0; + } while (time_before(jiffies, deadline)); + + return -ETIMEDOUT; +} + +static int cxl_reset_disable_cache(struct pci_dev *pdev, int dvsec, u16 cap) +{ + int rc, rc2; + + rc = cxl_reset_modify_ctrl2(pdev, dvsec, + PCI_DVSEC_CXL_DISABLE_CACHING, 0); + if (rc) + return rc; + + if (!(cap & PCI_DVSEC_CXL_CACHE_WBI_CAPABLE)) + return 0; + + rc = cxl_reset_wait_cache_wbi(pdev, dvsec); + if (!rc) + return 0; + + /* + * Restore the default CXL.cache policy after error paths that + * successfully set DISABLE_CACHING before reset completion. + */ + rc2 = cxl_reset_enable_cache(pdev, dvsec); + if (rc2) + pci_warn(pdev, "failed to re-enable CXL caching: %d\n", rc2); + + return rc; +} + +static int cxl_reset_wait_done(struct pci_dev *pdev, int dvsec, u16 cap) +{ + unsigned long deadline; + u32 timeout_ms; + u16 status2; + bool final = false; + int idx, rc; + + idx = FIELD_GET(PCI_DVSEC_CXL_RST_TIMEOUT, cap); + if (idx >= ARRAY_SIZE(cxl_reset_timeout_ms)) { + int last = ARRAY_SIZE(cxl_reset_timeout_ms) - 1; + + pci_warn(pdev, + "unknown CXL reset timeout encoding %d; using %u ms\n", + idx, cxl_reset_timeout_ms[last]); + idx = last; + } + + timeout_ms = max_t(u32, cxl_reset_timeout_ms[idx], + CXL_RESET_RRS_WAIT_MS); + msleep(CXL_RESET_RRS_WAIT_MS); + deadline = jiffies + msecs_to_jiffies(timeout_ms - + CXL_RESET_RRS_WAIT_MS); + + do { + rc = pci_read_config_word(pdev, dvsec + PCI_DVSEC_CXL_STATUS2, + &status2); + if (rc) + return pcibios_err_to_errno(rc); + + if (status2 != U16_MAX) { + if (status2 & PCI_DVSEC_CXL_RST_ERR) + return -EIO; + + if (status2 & PCI_DVSEC_CXL_RST_DONE) + return 0; + } + + if (time_after_eq(jiffies, deadline)) { + if (final) + return -ETIMEDOUT; + final = true; + continue; + } + + msleep(CXL_RESET_STATUS_POLL_MS); + } while (true); +} + +static int cxl_reset_execute(struct pci_dev *pdev, int dvsec, u16 cap) +{ + bool target_prepared = false; + int rc, rc2; + + rc = cxl_reset_disable_cache(pdev, dvsec, cap); + if (rc) + return rc; + + if (!pci_wait_for_pending_transaction(pdev)) + pci_err(pdev, "timed out waiting for pending transactions\n"); + + rc = pci_dev_reset_iommu_prepare(pdev); + if (rc) + pci_err(pdev, "failed to stop IOMMU for CXL reset: %d\n", rc); + else + target_prepared = true; + + if (!rc) + rc = cxl_reset_initiate(pdev, dvsec); + if (!rc) + rc = cxl_reset_wait_done(pdev, dvsec, cap); + + rc2 = cxl_reset_enable_cache(pdev, dvsec); + if (rc2 && rc) + pci_warn(pdev, "failed to re-enable CXL caching: %d\n", rc2); + else if (rc2) + rc = rc2; + + if (target_prepared) + pci_dev_reset_iommu_done(pdev); + return rc; +} + +int cxl_reset_function(struct pci_dev *pdev, bool probe) +{ + int dvsec; + u16 cap; + + dvsec = cxl_reset_get_dvsec(pdev, &cap); + if (dvsec < 0) + return dvsec; + + if (probe) + return 0; + + return cxl_reset_execute(pdev, dvsec, cap); +} diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h index c8070d9cfbfb..856abbcd5f18 100644 --- a/include/cxl/cxl.h +++ b/include/cxl/cxl.h @@ -9,6 +9,7 @@ #include #include #include +#include #include /** @@ -165,6 +166,7 @@ struct cxl_hdm_info { #ifdef CONFIG_CXL_RESET void pci_cxl_hdm_init(struct pci_dev *pdev); void pci_cxl_hdm_release(struct pci_dev *pdev); +int cxl_reset_function(struct pci_dev *pdev, bool probe); #else static inline void pci_cxl_hdm_init(struct pci_dev *pdev) { @@ -173,6 +175,11 @@ static inline void pci_cxl_hdm_init(struct pci_dev *pdev) static inline void pci_cxl_hdm_release(struct pci_dev *pdev) { } + +static inline int cxl_reset_function(struct pci_dev *pdev, bool probe) +{ + return -ENOTTY; +} #endif struct cxl_reg_map { diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h index facaa324bd86..4f5942ebd29b 100644 --- a/include/uapi/linux/pci_regs.h +++ b/include/uapi/linux/pci_regs.h @@ -1352,8 +1352,22 @@ #define PCI_DVSEC_CXL_CACHE_CAPABLE _BITUL(0) #define PCI_DVSEC_CXL_MEM_CAPABLE _BITUL(2) #define PCI_DVSEC_CXL_HDM_COUNT __GENMASK(5, 4) +#define PCI_DVSEC_CXL_CACHE_WBI_CAPABLE _BITUL(6) +#define PCI_DVSEC_CXL_RST_CAPABLE _BITUL(7) +#define PCI_DVSEC_CXL_RST_TIMEOUT __GENMASK(10, 8) +#define PCI_DVSEC_CXL_RST_MEM_CLR_CAPABLE _BITUL(11) #define PCI_DVSEC_CXL_CTRL 0xC +#define PCI_DVSEC_CXL_CACHE_ENABLE _BITUL(0) #define PCI_DVSEC_CXL_MEM_ENABLE _BITUL(2) +#define PCI_DVSEC_CXL_CTRL2 0x10 +#define PCI_DVSEC_CXL_DISABLE_CACHING _BITUL(0) +#define PCI_DVSEC_CXL_INIT_CACHE_WBI _BITUL(1) +#define PCI_DVSEC_CXL_INIT_CXL_RST _BITUL(2) +#define PCI_DVSEC_CXL_RST_MEM_CLR_EN _BITUL(3) +#define PCI_DVSEC_CXL_STATUS2 0x12 +#define PCI_DVSEC_CXL_CACHE_INV _BITUL(0) +#define PCI_DVSEC_CXL_RST_DONE _BITUL(1) +#define PCI_DVSEC_CXL_RST_ERR _BITUL(2) #define PCI_DVSEC_CXL_RANGE_SIZE_HIGH(i) (0x18 + (i * 0x10)) #define PCI_DVSEC_CXL_RANGE_SIZE_LOW(i) (0x1C + (i * 0x10)) #define PCI_DVSEC_CXL_MEM_INFO_VALID _BITUL(0) -- 2.43.0