[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v2 10/11] xen/arm: Do not map PCI ECAM and MMIO space to Domain-0's p2m
On 25.09.21 03:44, Stefano Stabellini wrote: > On Thu, 23 Sep 2021, 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. >> >> [1] >> https://urldefense.com/v3/__https://lists.xenproject.org/archives/html/xen-devel/2020-07/msg00777.html__;!!GF_29dbcQIUBPA!lrCuNRzUVkRf4FLgp3hW-4uOldgKr4qNpZb_ufI0jW-O0eRH11VFDeGcs5pPdtKZT1_ou4InSg$ >> [lists[.]xenproject[.]org] >> [2] >> https://urldefense.com/v3/__https://www.kernel.org/doc/Documentation/devicetree/bindings/pci/host-generic-pci.txt__;!!GF_29dbcQIUBPA!lrCuNRzUVkRf4FLgp3hW-4uOldgKr4qNpZb_ufI0jW-O0eRH11VFDeGcs5pPdtKZT1_T5yn7GA$ >> [kernel[.]org] >> [3] >> https://urldefense.com/v3/__https://www.kernel.org/doc/Documentation/devicetree/bindings/pci/hisilicon-pcie.txt__;!!GF_29dbcQIUBPA!lrCuNRzUVkRf4FLgp3hW-4uOldgKr4qNpZb_ufI0jW-O0eRH11VFDeGcs5pPdtKZT18im_Y2tw$ >> [kernel[.]org] >> >> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx> >> >> --- >> 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 | 38 +++++++++++++++-------- >> xen/arch/arm/pci/ecam.c | 14 +++++++++ >> xen/arch/arm/pci/pci-host-common.c | 48 ++++++++++++++++++++++++++++++ >> xen/arch/arm/pci/pci-host-zynqmp.c | 1 + >> xen/include/asm-arm/pci.h | 9 ++++++ >> xen/include/asm-arm/setup.h | 13 ++++++++ >> 6 files changed, 111 insertions(+), 12 deletions(-) >> >> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c >> index 83ab0d52cce9..e72c1b881cae 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> >> #include <xen/libfdt/libfdt.h> >> #include <xen/guest_access.h> >> #include <xen/iocap.h> >> @@ -47,12 +46,6 @@ 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)) >> @@ -1388,9 +1381,8 @@ static int __init map_dt_irq_to_domain(const struct >> dt_device_node *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; >> @@ -1417,6 +1409,13 @@ static int __init map_range_to_domain(const struct >> dt_device_node *dev, >> } >> } >> >> +#ifdef CONFIG_HAS_PCI >> + if ( is_pci_passthrough_enabled() && >> + (device_get_class(dev) == DEVICE_PCI) && >> + !mr_data->map_pci_bridge ) >> + need_mapping = false; >> +#endif > With the change I suggested below turning map_pci_bridge into > skip_mapping, then this check could go away if we just set need_mapping > as follows: > > bool need_mapping = !dt_device_for_passthrough(dev) && > !mr_data->skip_mapping; Not exactly. This check, e.g. "is_pci_passthrough_enabled() && (device_get_class(dev) == DEVICE_PCI)" really protects us from mapping any of the ranges belonging to a PCI device: we scan the device tree and for each node we call map_range_to_domain with skip_mapping == false (it is called from map_device_children). So, if there is no check then the mapping is performed even for PCI devices which we do not want. But, yes we can simplify the logic to: bool need_mapping = !dt_device_for_passthrough(dev) && !mr_data->skip_mapping; #ifdef CONFIG_HAS_PCI if ( need_mapping && is_pci_passthrough_enabled() && (device_get_class(dev) == DEVICE_PCI) ) need_mapping = false; #endif but I see no big profit from it. > > >> if ( need_mapping ) >> { >> res = map_regions_p2mt(d, >> @@ -1450,7 +1449,11 @@ static int __init map_device_children(struct domain >> *d, >> const struct dt_device_node *dev, >> p2m_type_t p2mt) >> { >> - struct map_range_data mr_data = { .d = d, .p2mt = p2mt }; >> + struct map_range_data mr_data = { >> + .d = d, >> + .p2mt = p2mt, >> + .map_pci_bridge = false >> + }; >> int ret; >> >> if ( dt_device_type_is_equal(dev, "pci") ) >> @@ -1582,7 +1585,11 @@ static int __init handle_device(struct domain *d, >> struct dt_device_node *dev, >> /* Give permission and map MMIOs */ >> for ( i = 0; i < naddr; i++ ) >> { >> - struct map_range_data mr_data = { .d = d, .p2mt = p2mt }; >> + struct map_range_data mr_data = { >> + .d = d, >> + .p2mt = p2mt, >> + .map_pci_bridge = false >> + }; >> res = dt_device_get_address(dev, i, &addr, &size); >> if ( res ) >> { >> @@ -2754,7 +2761,14 @@ static int __init construct_dom0(struct domain *d) >> return rc; >> >> if ( acpi_disabled ) >> + { >> rc = prepare_dtb_hwdom(d, &kinfo); >> +#ifdef CONFIG_HAS_PCI >> + if ( rc < 0 ) >> + return rc; > This doesn't look great :-) > > I would move the call to pci_host_bridge_mappings() below just before > construct_domain. I put it there for purpose: currently we only support device-tree and ACPI is not covered, e.g. pci_host_bridge_mappings is implemented with device-tree in mind. So, I decided to tie it to prepare_dtb_hwdom which is called when acpi_disabled is true. > > >> + rc = pci_host_bridge_mappings(d, p2m_mmio_direct_c); >> +#endif >> + } >> else >> rc = prepare_acpi(d, &kinfo); >> >> diff --git a/xen/arch/arm/pci/ecam.c b/xen/arch/arm/pci/ecam.c >> index 9b88b1cedaa2..eae177f2cbc2 100644 >> --- a/xen/arch/arm/pci/ecam.c >> +++ b/xen/arch/arm/pci/ecam.c >> @@ -39,6 +39,19 @@ void __iomem *pci_ecam_map_bus(struct pci_host_bridge >> *bridge, >> return base + (PCI_DEVFN2(sbdf) << devfn_shift) + where; >> } >> >> +bool pci_ecam_need_p2m_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, >> @@ -46,6 +59,7 @@ 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_mapping = pci_ecam_need_p2m_mapping, >> } >> }; >> >> diff --git a/xen/arch/arm/pci/pci-host-common.c >> b/xen/arch/arm/pci/pci-host-common.c >> index 155f2a2743af..f350826ea26b 100644 >> --- a/xen/arch/arm/pci/pci-host-common.c >> +++ b/xen/arch/arm/pci/pci-host-common.c >> @@ -18,6 +18,7 @@ >> >> #include <xen/init.h> >> #include <xen/pci.h> >> +#include <asm/setup.h> >> #include <xen/rwlock.h> >> #include <xen/sched.h> >> #include <xen/vmap.h> >> @@ -328,6 +329,53 @@ int pci_host_get_num_bridges(void) >> return count; >> } >> >> +int __init pci_host_bridge_mappings(struct domain *d, p2m_type_t p2mt) >> +{ >> + struct pci_host_bridge *bridge; >> + struct map_range_data mr_data = { >> + .d = d, >> + .p2mt = p2mt, >> + .map_pci_bridge = true >> + }; >> + >> + /* >> + * 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" or "assigned-addresses" device tree property. >> + * Neither we want to map any of the MMIO ranges found in the "ranges" >> + * device tree property. >> + */ >> + list_for_each_entry( bridge, &pci_host_bridges, node ) >> + { >> + const struct dt_device_node *dev = bridge->dt_node; >> + int i; > i should be unsigned int Ok > > >> + 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 %u for %s\n", > Maybe rephrase it to: > > Unable to retrieve address range index=%u for %s This is a copy-paste from the original code, but ok > > >> + i, dt_node_full_name(dev)); >> + return err; >> + } >> + >> + if ( bridge->ops->need_p2m_mapping(d, bridge, addr) ) > The current implementation of need_p2m_mapping filters out ECAM and > nothing else. Just double-checking here: is there anything else we > should filter out? Looking at the device tree pci node for ZynqMP: > > reg = <0x0 0xfd0e0000 0x0 0x1000 0x0 0xfd480000 0x0 > 0x1000 0x80 0x0 0x0 0x1000000>; > reg-names = "breg", "pcireg", "cfg"; > > We are filtering out cfg, but do we need both "breg" and "pcireg" here? It is vice versa: we are filtering out cfg only and all the rest are "unknown regions we do not want to alter". > > If not, do we need another function like .cfg_reg_index to know what we > actually need to map? I was thinking to use .cfg_reg_index fir that, but it means I'll need to traverse the device-tree to get the value for .cfg_reg_index which is already known to the bridge. So, it is cheaper to have a callback and just check that cfg->phys_addr != addr, e.g. what we want to map is not cfg. > > >> + { >> + 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 c27b4ea9f02f..adbe3627871f 100644 >> --- a/xen/arch/arm/pci/pci-host-zynqmp.c >> +++ b/xen/arch/arm/pci/pci-host-zynqmp.c >> @@ -33,6 +33,7 @@ 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_mapping = pci_ecam_need_p2m_mapping, >> } >> }; >> >> diff --git a/xen/include/asm-arm/pci.h b/xen/include/asm-arm/pci.h >> index 7618f0b6725b..b81f66e813ef 100644 >> --- a/xen/include/asm-arm/pci.h >> +++ b/xen/include/asm-arm/pci.h >> @@ -19,6 +19,8 @@ >> >> #ifdef CONFIG_HAS_PCI >> >> +#include <asm/p2m.h> >> + >> #define pci_to_dev(pcidev) (&(pcidev)->arch.dev) >> #define PRI_pci "%04x:%02x:%02x.%u" >> >> @@ -79,6 +81,9 @@ struct pci_ops { >> uint32_t reg, uint32_t len, uint32_t *value); >> int (*write)(struct pci_host_bridge *bridge, uint32_t sbdf, >> uint32_t reg, uint32_t len, uint32_t value); >> + bool (*need_p2m_mapping)(struct domain *d, >> + struct pci_host_bridge *bridge, >> + uint64_t addr); > I would call this function: need_p2m_hwdom_mapping Ok > > >> }; >> >> /* >> @@ -102,6 +107,9 @@ int pci_generic_config_write(struct pci_host_bridge >> *bridge, uint32_t sbdf, >> uint32_t reg, uint32_t len, uint32_t value); >> void __iomem *pci_ecam_map_bus(struct pci_host_bridge *bridge, >> uint32_t sbdf, uint32_t where); >> +bool pci_ecam_need_p2m_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); >> int pci_get_host_bridge_segment(const struct dt_device_node *node, >> uint16_t *segment); >> @@ -116,6 +124,7 @@ int pci_host_iterate_bridges(struct domain *d, >> int (*clb)(struct domain *d, >> struct pci_host_bridge *bridge)); >> int pci_host_get_num_bridges(void); >> +int pci_host_bridge_mappings(struct domain *d, p2m_type_t p2mt); >> #else /*!CONFIG_HAS_PCI*/ >> >> #define pci_passthrough_enabled (false) >> diff --git a/xen/include/asm-arm/setup.h b/xen/include/asm-arm/setup.h >> index 95da0b7ab9cd..21863dd2bc58 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 mappings for PCI host bridges must not be skipped. */ >> + bool map_pci_bridge; > To make this more generally applicable, I would call the new property: > > bool skip_mapping; Sounds good > > and it could apply to any class of devices. All current users would set > it to false except for pci_host_bridge_mappings. Please see PCI special case above > > >> +}; >> >> 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: >> -- >> 2.25.1 >>
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