From bcce8c74f1ce1e2731ac0261287897e3768767d8 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 24 Oct 2025 15:46:21 -0700 Subject: PCI: Enable host bridge emulation for PCI_DOMAINS_GENERIC platforms The ability to emulate a host bridge is useful not only for hardware PCI controllers like CONFIG_VMD, or virtual PCI controllers like CONFIG_PCI_HYPERV, but also for test and development scenarios like CONFIG_SAMPLES_DEVSEC [1]. One stumbling block for defining CONFIG_SAMPLES_DEVSEC, a sample implementation of a platform TSM for PCI Device Security, is the need to accommodate PCI_DOMAINS_GENERIC architectures alongside x86 [2]. In support of supplementing the existing CONFIG_PCI_BRIDGE_EMUL infrastructure for host bridges: * Introduce pci_bus_find_emul_domain_nr() as a common way to find a free PCI domain number whether that is to reuse the existing dynamic allocation code in the !ACPI case, or to assign an unused domain above the last ACPI segment. * Convert pci-hyperv to the new allocator so that the PCI core can unconditionally assume that bridge->domain_nr != PCI_DOMAIN_NR_NOT_SET is the dynamically allocated case. A follow on patch can also convert vmd to the new scheme. Currently vmd is limited to CONFIG_PCI_DOMAINS_GENERIC=n (x86) so, unlike pci-hyperv, it does not immediately conflict with this new pci_bus_find_emul_domain_nr() mechanism. Link: http://lore.kernel.org/174107249038.1288555.12362100502109498455.stgit@dwillia2-xfh.jf.intel.com [1] Reported-by: Suzuki K Poulose Closes: http://lore.kernel.org/20250311144601.145736-3-suzuki.poulose@arm.com [2] Signed-off-by: Dan Williams Signed-off-by: Bjorn Helgaas Tested-by: Suzuki K Poulose Tested-by: Michael Kelley Reviewed-by: Michael Kelley Cc: Lorenzo Pieralisi Cc: Manivannan Sadhasivam Cc: Rob Herring Cc: K. Y. Srinivasan Cc: Haiyang Zhang Cc: Wei Liu Cc: Dexuan Cui Link: https://patch.msgid.link/20251024224622.1470555-2-dan.j.williams@intel.com --- include/linux/pci.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/linux') diff --git a/include/linux/pci.h b/include/linux/pci.h index d1fdf81fbe1e..1ef1535802b0 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1956,10 +1956,17 @@ DEFINE_GUARD(pci_dev, struct pci_dev *, pci_dev_lock(_T), pci_dev_unlock(_T)) */ #ifdef CONFIG_PCI_DOMAINS extern int pci_domains_supported; +int pci_bus_find_emul_domain_nr(u32 hint, u32 min, u32 max); +void pci_bus_release_emul_domain_nr(int domain_nr); #else enum { pci_domains_supported = 0 }; static inline int pci_domain_nr(struct pci_bus *bus) { return 0; } static inline int pci_proc_domain(struct pci_bus *bus) { return 0; } +static inline int pci_bus_find_emul_domain_nr(u32 hint, u32 min, u32 max) +{ + return 0; +} +static inline void pci_bus_release_emul_domain_nr(int domain_nr) { } #endif /* CONFIG_PCI_DOMAINS */ /* -- cgit v1.2.3