On Wed, 20 Aug 2025, Mykyta Poturai wrote: > From: Edward Pickup <edward.pic...@arm.com> > > This patch adds a Xen boot arguments that, if enabled, causes a call to > existing code to scan pci devices enumerated by the firmware. > > This will be needed ahead of dom0less support for pci passthrough on > arm. > > Signed-off-by: Luca Fancellu <luca.fance...@arm.com> > Signed-off-by: Mykyta Poturai <mykyta_potu...@epam.com>
Acked-by: Stefano Stabellini <sstabell...@kernel.org> > --- > (cherry picked from commit bce463e1588a45e1bfdf59fc0d5f88b16604e439 from > the downstream branch poc/pci-passthrough from > https://gitlab.com/xen-project/people/bmarquis/xen-arm-poc.git) > > v1->v2: > * remove is_pci_scan_enabled wrapper > * make pci_scan_enabled ro_after_init > * drop debug prints > * drop Edward's SOB > > changes since cherry-pick: > * s/always_inline/inline/ > * replace additional kconfig option with config DEBUG > > Signed-off-by: Stewart Hildebrand <stewart.hildebr...@amd.com> > --- > docs/misc/xen-command-line.pandoc | 7 +++++++ > xen/arch/arm/include/asm/pci.h | 3 +++ > xen/arch/arm/pci/pci-host-common.c | 1 + > xen/arch/arm/pci/pci.c | 24 ++++++++++++++++++++++-- > 4 files changed, 33 insertions(+), 2 deletions(-) > > diff --git a/docs/misc/xen-command-line.pandoc > b/docs/misc/xen-command-line.pandoc > index a75b6c9301..762a1a4f5f 100644 > --- a/docs/misc/xen-command-line.pandoc > +++ b/docs/misc/xen-command-line.pandoc > @@ -2059,6 +2059,13 @@ This option can be specified more than once (up to 8 > times at present). > > Flag to enable or disable support for PCI passthrough > > +### pci-scan (arm) > +> `= <boolean>` > + > +> Default: `false` > + > +Flag to enable or disable Xen PCI scan at boot. > + > ### pcid (x86) > > `= <boolean> | xpti=<bool>` > > diff --git a/xen/arch/arm/include/asm/pci.h b/xen/arch/arm/include/asm/pci.h > index 08ffcd4438..7289f7688b 100644 > --- a/xen/arch/arm/include/asm/pci.h > +++ b/xen/arch/arm/include/asm/pci.h > @@ -23,6 +23,7 @@ > #define pci_to_dev(pcidev) (&(pcidev)->arch.dev) > > extern bool pci_passthrough_enabled; > +extern bool pci_scan_enabled; > > struct rangeset; > > @@ -155,6 +156,8 @@ bool arch_pci_device_physdevop(void); > > #else /*!CONFIG_HAS_PCI*/ > > +#define pci_scan_enabled false > + > struct pci_dev; > > static inline void arch_pci_init_pdev(struct pci_dev *pdev) {} > diff --git a/xen/arch/arm/pci/pci-host-common.c > b/xen/arch/arm/pci/pci-host-common.c > index 487c545f3a..d3481b05eb 100644 > --- a/xen/arch/arm/pci/pci-host-common.c > +++ b/xen/arch/arm/pci/pci-host-common.c > @@ -284,6 +284,7 @@ pci_host_common_probe(struct dt_device_node *dev, > } > > pci_add_host_bridge(bridge); > + pci_add_segment(bridge->segment); > > return bridge; > > diff --git a/xen/arch/arm/pci/pci.c b/xen/arch/arm/pci/pci.c > index beb1f971fa..1b34e17517 100644 > --- a/xen/arch/arm/pci/pci.c > +++ b/xen/arch/arm/pci/pci.c > @@ -91,8 +91,14 @@ bool arch_pci_device_physdevop(void) > bool __read_mostly pci_passthrough_enabled; > boolean_param("pci-passthrough", pci_passthrough_enabled); > > +/* By default pci scan is disabled. */ > +bool __ro_after_init pci_scan_enabled; > +boolean_param("pci-scan", pci_scan_enabled); > + > static int __init pci_init(void) > { > + int ret; > + > /* > * Enable PCI passthrough when has been enabled explicitly > * (pci-passthrough=on). > @@ -104,9 +110,23 @@ static int __init pci_init(void) > panic("Could not initialize PCI segment 0\n"); > > if ( acpi_disabled ) > - return dt_pci_init(); > + ret = dt_pci_init(); > else > - return acpi_pci_init(); > + ret = acpi_pci_init(); > + > + if ( ret < 0 ) > + return ret; > + > + if ( pci_scan_enabled ) > + { > + ret = scan_pci_devices(); > + > + if ( ret < 0 ) > + return ret; > + > + } > + > + return 0; > } > __initcall(pci_init); > > -- > 2.34.1 >
