From: Manish Honap <[email protected]> vfio-pci needs to run a CXL reset on a passed-through Type-2 device without the host-memory handling in cxl_reset_function(): the memory behind the decoder belongs to the guest, so the HDM range collection and host CPU cache flush that the host path performs must be skipped.
Add cxl_reset_dvsec_sequence(), which runs the DVSEC reset under the device lock and restores HDM state through cxl_restore_state_after_pci_reset(), and cxl_reset_capable() to gate it on a function-scoped reset. Both are exported to the vfio-cxl module so vfio-pci core does not import the CXL namespace. CXL Reset always clears memory, so there is no caller Memory Clear choice. Assisted-by: LLM Signed-off-by: Manish Honap <[email protected]> --- drivers/cxl/core/resource.c | 53 +++++++++++++++++++++++++++++++++++++ include/cxl/cxl.h | 12 +++++++++ 2 files changed, 65 insertions(+) diff --git a/drivers/cxl/core/resource.c b/drivers/cxl/core/resource.c index d3491e20c1ca..d373df9aa127 100644 --- a/drivers/cxl/core/resource.c +++ b/drivers/cxl/core/resource.c @@ -1398,3 +1398,56 @@ int cxl_reset_function(struct pci_dev *pdev, bool probe) cxl_pci_target_reset_done(pdev, &target_prepared); return rc; } + +/* True when a function-scoped CXL reset is available for @pdev. */ +bool cxl_reset_capable(struct pci_dev *pdev) +{ + u16 cap; + + if (cxl_reset_get_dvsec(pdev, &cap) < 0) + return false; + + if (pdev->multifunction || pci_num_vf(pdev)) + return false; + + return cxl_reset_hdm_available(pdev); +} +EXPORT_SYMBOL_FOR_MODULES(cxl_reset_capable, "vfio-cxl"); + +/* + * Run the DVSEC reset sequence and restore HDM state for a caller that owns + * device quiesce and PCI config save/restore, such as vfio-pci. + * The HDM range collection and host CPU cache flush that cxl_reset_function() + * performs for host-owned memory are skipped as that memory belongs to the + * guest. + */ +int cxl_reset_dvsec_sequence(struct pci_dev *pdev) +{ + bool target_prepared = false; + bool reset_initiated = false; + int dvsec; + int rc; + u16 cap; + + dvsec = cxl_reset_get_dvsec(pdev, &cap); + if (dvsec < 0) + return dvsec; + + if (pdev->multifunction || pci_num_vf(pdev)) + return -ENOTTY; + + if (!pci_dev_trylock(pdev)) + return -EBUSY; + + rc = cxl_reset_execute(pdev, &target_prepared, &reset_initiated, dvsec, + cap); + if (!rc) + rc = cxl_restore_state_after_pci_reset(pdev); + else if (reset_initiated) + cxl_reset_save_disabled_state(pdev); + + cxl_pci_target_reset_done(pdev, &target_prepared); + pci_dev_unlock(pdev); + return rc; +} +EXPORT_SYMBOL_FOR_MODULES(cxl_reset_dvsec_sequence, "vfio-cxl"); diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h index 92314f67b702..a28903fc2960 100644 --- a/include/cxl/cxl.h +++ b/include/cxl/cxl.h @@ -168,6 +168,8 @@ void pci_cxl_hdm_init(struct pci_dev *pdev); void pci_cxl_hdm_release(struct pci_dev *pdev); int cxl_restore_state_after_pci_reset(struct pci_dev *pdev); int cxl_reset_function(struct pci_dev *pdev, bool probe); +bool cxl_reset_capable(struct pci_dev *pdev); +int cxl_reset_dvsec_sequence(struct pci_dev *pdev); #else static inline void pci_cxl_hdm_init(struct pci_dev *pdev) { @@ -186,6 +188,16 @@ static inline int cxl_reset_function(struct pci_dev *pdev, bool probe) { return -ENOTTY; } + +static inline bool cxl_reset_capable(struct pci_dev *pdev) +{ + return false; +} + +static inline int cxl_reset_dvsec_sequence(struct pci_dev *pdev) +{ + return -ENOTTY; +} #endif struct cxl_reg_map { -- 2.25.1
