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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v6 4/7] xen/arm: do not map PCI ECAM and MMIO space to Domain-0's p2m
Hi, Julien! On 23.11.21 18:42, Julien Grall wrote: > Hi Oleksandr, > > On 05/11/2021 06:33, Oleksandr Andrushchenko wrote: >> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx> >> >> PCI host bridges are special devices in terms of implementing PCI >> passthrough. According to [1] the current implementation depends on >> Domain-0 to perform the initialization of the relevant PCI host >> bridge hardware and perform PCI device enumeration. In order to >> achieve that one of the required changes is to not map all the memory >> ranges in map_range_to_domain as we traverse the device tree on startup >> and perform some additional checks if the range needs to be mapped to >> Domain-0. >> >> The generic PCI host controller device tree binding says [2]: >> - ranges: As described in IEEE Std 1275-1994, but must provide >> at least a definition of non-prefetchable memory. One >> or both of prefetchable Memory and IO Space may also >> be provided. >> >> - reg : The Configuration Space base address and size, as accessed >> from the parent bus. The base address corresponds to >> the first bus in the "bus-range" property. If no >> "bus-range" is specified, this will be bus 0 (the default). >> >> From the above none of the memory ranges from the "ranges" property >> needs to be mapped to Domain-0 at startup as MMIO mapping is going to >> be handled dynamically by vPCI as we assign PCI devices, e.g. each >> device assigned to Domain-0/guest will have its MMIOs mapped/unmapped >> as needed by Xen. >> >> The "reg" property covers not only ECAM space, but may also have other >> then the configuration memory ranges described, for example [3]: >> - reg: Should contain rc_dbi, config registers location and length. >> - reg-names: Must include the following entries: >> "rc_dbi": controller configuration registers; >> "config": PCIe configuration space registers. >> >> This patch makes it possible to not map all the ranges from the >> "ranges" property and also ECAM from the "reg". All the rest from the >> "reg" property still needs to be mapped to Domain-0, so the PCI >> host bridge remains functional in Domain-0. > > The commit message is explaining the problematic quite well (thanks for > that). I think it also wants to explain the approach taken (the fact that we > are deferring the mapping for hostbridges). Will add > >> >> [1] >> https://urldefense.com/v3/__https://lists.xenproject.org/archives/html/xen-devel/2020-07/msg00777.html__;!!GF_29dbcQIUBPA!mdKldRDDMc62Zlr3zHPdIXeXjHNI2H6pGE7ZHNvbK3xizCNe0mhV7jMF5WLGZ7bA5B47tK4zFA$ >> [lists[.]xenproject[.]org] >> [2] >> https://urldefense.com/v3/__https://www.kernel.org/doc/Documentation/devicetree/bindings/pci/host-generic-pci.txt__;!!GF_29dbcQIUBPA!mdKldRDDMc62Zlr3zHPdIXeXjHNI2H6pGE7ZHNvbK3xizCNe0mhV7jMF5WLGZ7bA5B7UwSKSww$ >> [kernel[.]org] >> [3] >> https://urldefense.com/v3/__https://www.kernel.org/doc/Documentation/devicetree/bindings/pci/hisilicon-pcie.txt__;!!GF_29dbcQIUBPA!mdKldRDDMc62Zlr3zHPdIXeXjHNI2H6pGE7ZHNvbK3xizCNe0mhV7jMF5WLGZ7bA5B6NizsNXQ$ >> [kernel[.]org] >> >> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx> >> --- >> Since v5: >> - remove some need_mapping local variables >> - use own_device in handle_device >> - add __init for pci_ecam_need_p2m_hwdom_mapping >> - make pci_host_bridge_mappings use p2m_mmio_direct_dev directly >> Since v4: >> - update skip_mapping comment >> - add comment why we need to map interrupts to Dom0 >> Since v3: >> - pass struct map_range_data to map_dt_irq_to_domain >> - remove redundant check from map_range_to_domain >> - fix handle_device's .skip_mapping >> Since v2: >> - removed check in map_range_to_domain for PCI_DEV >> and moved it to handle_device, so the code is >> simpler >> - s/map_pci_bridge/skip_mapping >> - extended comment in pci_host_bridge_mappings >> - minor code restructure in construct_dom0 >> - s/.need_p2m_mapping/.need_p2m_hwdom_mapping and related >> callbacks >> - unsigned int i; in pci_host_bridge_mappings >> Since v1: >> - Added better description of why and what needs to be mapped into >> Domain-0's p2m and what doesn't >> - Do not do any mappings for PCI devices while traversing the DT >> - Walk all the bridges and make required mappings in one go >> --- >> xen/arch/arm/domain_build.c | 67 +++++++++++++++++------------- >> xen/arch/arm/pci/ecam.c | 14 +++++++ >> xen/arch/arm/pci/pci-host-common.c | 50 ++++++++++++++++++++++ >> xen/arch/arm/pci/pci-host-zynqmp.c | 1 + >> xen/include/asm-arm/pci.h | 10 +++++ >> xen/include/asm-arm/setup.h | 13 ++++++ >> 6 files changed, 126 insertions(+), 29 deletions(-) >> >> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c >> index f7fcb1400c19..c7d992456ca7 100644 >> --- a/xen/arch/arm/domain_build.c >> +++ b/xen/arch/arm/domain_build.c >> @@ -10,7 +10,6 @@ >> #include <asm/regs.h> >> #include <xen/errno.h> >> #include <xen/err.h> >> -#include <xen/device_tree.h> > > You are still using helpers defined by this header. So I would keep the > include even if it may have been included by another one. Sure, will remove this change > >> #include <xen/libfdt/libfdt.h> >> #include <xen/guest_access.h> >> #include <xen/iocap.h> >> @@ -51,12 +50,6 @@ static int __init parse_dom0_mem(const char *s) >> } >> custom_param("dom0_mem", parse_dom0_mem); >> -struct map_range_data >> -{ >> - struct domain *d; >> - p2m_type_t p2mt; >> -}; >> - >> /* Override macros from asm/page.h to make them work with mfn_t */ >> #undef virt_to_mfn >> #define virt_to_mfn(va) _mfn(__virt_to_mfn(va)) >> @@ -1676,10 +1669,10 @@ static int __init map_dt_irq_to_domain(const struct >> dt_device_node *dev, >> const struct dt_irq *dt_irq, >> void *data) >> { >> - struct domain *d = data; >> + struct map_range_data *mr_data = data; >> + struct domain *d = mr_data->d; >> unsigned int irq = dt_irq->irq; >> int res; >> - bool need_mapping = !dt_device_for_passthrough(dev); >> if ( irq < NR_LOCAL_IRQS ) >> { >> @@ -1698,18 +1691,16 @@ static int __init map_dt_irq_to_domain(const struct >> dt_device_node *dev, >> return res; >> } >> - res = map_irq_to_domain(d, irq, need_mapping, dt_node_name(dev)); >> + res = map_irq_to_domain(d, irq, !mr_data->skip_mapping, >> dt_node_name(dev)); >> return 0; >> } >> -static int __init map_range_to_domain(const struct dt_device_node *dev, >> - u64 addr, u64 len, >> - void *data) >> +int __init map_range_to_domain(const struct dt_device_node *dev, >> + u64 addr, u64 len, void *data) >> { >> struct map_range_data *mr_data = data; >> struct domain *d = mr_data->d; >> - bool need_mapping = !dt_device_for_passthrough(dev); >> int res; >> res = iomem_permit_access(d, paddr_to_pfn(addr), >> @@ -1723,7 +1714,7 @@ static int __init map_range_to_domain(const struct >> dt_device_node *dev, >> return res; >> } >> - if ( need_mapping ) >> + if ( !mr_data->skip_mapping ) >> { >> res = map_regions_p2mt(d, >> gaddr_to_gfn(addr), >> @@ -1752,23 +1743,21 @@ static int __init map_range_to_domain(const struct >> dt_device_node *dev, >> * then we may need to perform additional mappings in order to make >> * the child resources available to domain 0. >> */ >> -static int __init map_device_children(struct domain *d, >> - const struct dt_device_node *dev, >> - p2m_type_t p2mt) >> +static int __init map_device_children(const struct dt_device_node *dev, >> + struct map_range_data *mr_data) >> { >> - struct map_range_data mr_data = { .d = d, .p2mt = p2mt }; >> - int ret; >> - >> if ( dt_device_type_is_equal(dev, "pci") ) >> { >> + int ret; >> + >> dt_dprintk("Mapping children of %s to guest\n", >> dt_node_full_name(dev)); >> - ret = dt_for_each_irq_map(dev, &map_dt_irq_to_domain, d); >> + ret = dt_for_each_irq_map(dev, &map_dt_irq_to_domain, mr_data); >> if ( ret < 0 ) >> return ret; >> - ret = dt_for_each_range(dev, &map_range_to_domain, &mr_data); >> + ret = dt_for_each_range(dev, &map_range_to_domain, mr_data); >> if ( ret < 0 ) >> return ret; >> } >> @@ -1848,14 +1837,28 @@ static int __init handle_device(struct domain *d, >> struct dt_device_node *dev, >> unsigned int i; >> int res; >> u64 addr, size; >> - bool need_mapping = !dt_device_for_passthrough(dev); >> + bool own_device = !dt_device_for_passthrough(dev); >> + /* >> + * For PCI passthrough we only need to remap to Dom0 the interrupts >> + * and memory ranges from "reg" property which cover controller's >> + * configuration registers and such. PCIe configuration space registers >> + * of the PCIe Root Complex and PCIe aperture should not be mapped >> + * automatically to Dom0. >> + */ > > I would clarify in this comment (and the commit message) that this only cover > hostbridge that are been shared between dom0 and Xen. > > But I find the comment confusing because I would expect to explain this... > >> + struct map_range_data mr_data = { >> + .d = d, >> + .p2mt = p2mt, >> + .skip_mapping = !own_device || >> + (is_pci_passthrough_enabled() && >> + (device_get_class(dev) == DEVICE_PCI_HOSTBRIDGE)) > > ... line. Instead, it explains the global behavior. I would rework the > comment to something like: > > /* > * We want to avoid mappings the MMIO in dom0 for the following cases: > * - The device is owned by dom0 (i.e. it has been flagged for > * passthrough). > * - PCI hostbridges with driver in Xen. They will later on by > * pci_host_bridge_mappings(). > */ Ok, sounds good > >> + }; >> naddr = dt_number_of_address(dev); >> dt_dprintk("%s passthrough = %d naddr = %u\n", >> - dt_node_full_name(dev), need_mapping, naddr); >> + dt_node_full_name(dev), own_device, naddr); >> - if ( need_mapping ) >> + if ( own_device ) >> { >> dt_dprintk("Check if %s is behind the IOMMU and add it\n", >> dt_node_full_name(dev)); >> @@ -1881,14 +1884,13 @@ static int __init handle_device(struct domain *d, >> struct dt_device_node *dev, >> } >> } >> - res = handle_device_interrupts(d, dev, need_mapping); >> + res = handle_device_interrupts(d, dev, own_device); >> if ( res < 0 ) >> return res; >> /* Give permission and map MMIOs */ >> for ( i = 0; i < naddr; i++ ) >> { >> - struct map_range_data mr_data = { .d = d, .p2mt = p2mt }; >> res = dt_device_get_address(dev, i, &addr, &size); >> if ( res ) >> { >> @@ -1902,7 +1904,7 @@ static int __init handle_device(struct domain *d, >> struct dt_device_node *dev, >> return res; >> } >> - res = map_device_children(d, dev, p2mt); >> + res = map_device_children(dev, &mr_data); >> if ( res ) >> return res; >> @@ -3060,7 +3062,14 @@ static int __init construct_dom0(struct domain *d) >> return rc; >> if ( acpi_disabled ) >> + { >> rc = prepare_dtb_hwdom(d, &kinfo); >> + if ( rc < 0 ) >> + return rc; >> +#ifdef CONFIG_HAS_PCI >> + rc = pci_host_bridge_mappings(d); >> +#endif >> + } >> else >> rc = prepare_acpi(d, &kinfo); >> diff --git a/xen/arch/arm/pci/ecam.c b/xen/arch/arm/pci/ecam.c >> index 602d00799c8d..4f71b11c3057 100644 >> --- a/xen/arch/arm/pci/ecam.c >> +++ b/xen/arch/arm/pci/ecam.c >> @@ -40,6 +40,19 @@ void __iomem *pci_ecam_map_bus(struct pci_host_bridge >> *bridge, >> return base + (PCI_DEVFN2(sbdf.bdf) << devfn_shift) + where; >> } >> +bool __init pci_ecam_need_p2m_hwdom_mapping(struct domain *d, >> + struct pci_host_bridge *bridge, >> + uint64_t addr) >> +{ >> + struct pci_config_window *cfg = bridge->cfg; >> + >> + /* >> + * We do not want ECAM address space to be mapped in Domain-0's p2m, >> + * so we can trap access to it. >> + */ >> + return cfg->phys_addr != addr; >> +} >> + >> /* ECAM ops */ >> const struct pci_ecam_ops pci_generic_ecam_ops = { >> .bus_shift = 20, >> @@ -47,6 +60,7 @@ const struct pci_ecam_ops pci_generic_ecam_ops = { >> .map_bus = pci_ecam_map_bus, >> .read = pci_generic_config_read, >> .write = pci_generic_config_write, >> + .need_p2m_hwdom_mapping = pci_ecam_need_p2m_hwdom_mapping, >> } >> }; >> diff --git a/xen/arch/arm/pci/pci-host-common.c >> b/xen/arch/arm/pci/pci-host-common.c >> index 0d271a6e8881..6af845ab9d6c 100644 >> --- a/xen/arch/arm/pci/pci-host-common.c >> +++ b/xen/arch/arm/pci/pci-host-common.c >> @@ -22,6 +22,8 @@ >> #include <xen/sched.h> >> #include <xen/vmap.h> >> +#include <asm/setup.h> >> + >> /* >> * List for all the pci host bridges. >> */ >> @@ -316,6 +318,54 @@ unsigned int pci_host_get_num_bridges(void) >> return count; >> } >> +int __init pci_host_bridge_mappings(struct domain *d) >> +{ >> + struct pci_host_bridge *bridge; >> + struct map_range_data mr_data = { >> + .d = d, >> + .p2mt = p2m_mmio_direct_dev, >> + .skip_mapping = false >> + }; >> + >> + /* >> + * For each PCI host bridge we need to only map those ranges >> + * which are used by Domain-0 to properly initialize the bridge, >> + * e.g. we do not want to map ECAM configuration space which lives in >> + * "reg" device tree property, but we want to map other regions of >> + * the host bridge. The PCI aperture defined by the "ranges" device >> + * tree property should also be skipped. >> + */ > > This seems to explain the purpose of the function. So I would move the > commment on top of pci_host_bridge_mappings(). Makes sense > >> + list_for_each_entry( bridge, &pci_host_bridges, node ) >> + { >> + const struct dt_device_node *dev = bridge->dt_node; >> + unsigned int i; >> + >> + for ( i = 0; i < dt_number_of_address(dev); i++ ) >> + { >> + uint64_t addr, size; >> + int err; >> + >> + err = dt_device_get_address(dev, i, &addr, &size); >> + if ( err ) >> + { >> + printk(XENLOG_ERR >> + "Unable to retrieve address range index=%u for %s\n", >> + i, dt_node_full_name(dev)); >> + return err; >> + } >> + >> + if ( bridge->ops->need_p2m_hwdom_mapping(d, bridge, addr) ) >> + { >> + err = map_range_to_domain(dev, addr, size, &mr_data); >> + if ( err ) >> + return err; >> + } >> + } >> + } >> + >> + return 0; >> +} >> + >> /* >> * Local variables: >> * mode: C >> diff --git a/xen/arch/arm/pci/pci-host-zynqmp.c >> b/xen/arch/arm/pci/pci-host-zynqmp.c >> index 516982bca833..101edb8593c1 100644 >> --- a/xen/arch/arm/pci/pci-host-zynqmp.c >> +++ b/xen/arch/arm/pci/pci-host-zynqmp.c >> @@ -34,6 +34,7 @@ const struct pci_ecam_ops nwl_pcie_ops = { >> .map_bus = pci_ecam_map_bus, >> .read = pci_generic_config_read, >> .write = pci_generic_config_write, >> + .need_p2m_hwdom_mapping = pci_ecam_need_p2m_hwdom_mapping, >> } >> }; >> diff --git a/xen/include/asm-arm/pci.h b/xen/include/asm-arm/pci.h >> index 969333043431..3d706fdd1d88 100644 >> --- a/xen/include/asm-arm/pci.h >> +++ b/xen/include/asm-arm/pci.h >> @@ -17,6 +17,8 @@ >> #ifdef CONFIG_HAS_PCI >> +#include <asm/p2m.h> >> + >> #define pci_to_dev(pcidev) (&(pcidev)->arch.dev) >> extern bool pci_passthrough_enabled; >> @@ -73,6 +75,9 @@ struct pci_ops { >> uint32_t reg, uint32_t len, uint32_t *value); >> int (*write)(struct pci_host_bridge *bridge, pci_sbdf_t sbdf, >> uint32_t reg, uint32_t len, uint32_t value); >> + bool (*need_p2m_hwdom_mapping)(struct domain *d, >> + struct pci_host_bridge *bridge, >> + uint64_t addr); >> }; >> /* >> @@ -96,6 +101,9 @@ int pci_generic_config_write(struct pci_host_bridge >> *bridge, pci_sbdf_t sbdf, >> uint32_t reg, uint32_t len, uint32_t value); >> void __iomem *pci_ecam_map_bus(struct pci_host_bridge *bridge, >> pci_sbdf_t sbdf, uint32_t where); >> +bool pci_ecam_need_p2m_hwdom_mapping(struct domain *d, >> + struct pci_host_bridge *bridge, >> + uint64_t addr); >> struct pci_host_bridge *pci_find_host_bridge(uint16_t segment, uint8_t >> bus); >> struct dt_device_node *pci_find_host_bridge_node(struct device *dev); >> int pci_get_host_bridge_segment(const struct dt_device_node *node, >> @@ -115,6 +123,8 @@ int pci_host_iterate_bridges(struct domain *d, >> struct pci_host_bridge *bridge)); >> unsigned int pci_host_get_num_bridges(void); >> +int pci_host_bridge_mappings(struct domain *d); >> + >> #else /*!CONFIG_HAS_PCI*/ >> struct arch_pci_dev { }; >> diff --git a/xen/include/asm-arm/setup.h b/xen/include/asm-arm/setup.h >> index 95da0b7ab9cd..88d9673db817 100644 >> --- a/xen/include/asm-arm/setup.h >> +++ b/xen/include/asm-arm/setup.h >> @@ -2,6 +2,8 @@ >> #define __ARM_SETUP_H_ >> #include <public/version.h> >> +#include <asm/p2m.h> >> +#include <xen/device_tree.h> >> #define MIN_FDT_ALIGN 8 >> #define MAX_FDT_SIZE SZ_2M >> @@ -77,6 +79,14 @@ struct bootinfo { >> #endif >> }; >> +struct map_range_data >> +{ >> + struct domain *d; >> + p2m_type_t p2mt; >> + /* Set if mapping of the memory ranges must be skipped. */ >> + bool skip_mapping; >> +}; >> + >> extern struct bootinfo bootinfo; >> extern domid_t max_init_domid; >> @@ -124,6 +134,9 @@ void device_tree_get_reg(const __be32 **cell, u32 >> address_cells, >> u32 device_tree_get_u32(const void *fdt, int node, >> const char *prop_name, u32 dflt); >> +int map_range_to_domain(const struct dt_device_node *dev, >> + u64 addr, u64 len, void *data); >> + >> #endif >> /* >> * Local variables: >> > > Cheers, > Thank you, Oleksandr
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