On Tue, 5 Oct 2021, Oleksandr Andrushchenko wrote:
> On 05.10.21 04:24, Stefano Stabellini wrote:
> > On Mon, 4 Oct 2021, Oleksandr Andrushchenko wrote:
> >> From: Oleksandr Andrushchenko <[email protected]>
> >>
> >> 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://lists.xenproject.org/archives/html/xen-devel/2020-07/msg00777.html
> >> [2]
> >> https://www.kernel.org/doc/Documentation/devicetree/bindings/pci/host-generic-pci.txt
> >> [3]
> >> https://www.kernel.org/doc/Documentation/devicetree/bindings/pci/hisilicon-pcie.txt
> >>
> >> Signed-off-by: Oleksandr Andrushchenko <[email protected]>
> >> ---
> >> 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 | 50 ++++++++++++++++--------------
> >> xen/arch/arm/pci/ecam.c | 14 +++++++++
> >> xen/arch/arm/pci/pci-host-common.c | 49 +++++++++++++++++++++++++++++
> >> 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, 114 insertions(+), 23 deletions(-)
> >>
> >> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> >> index 8739e3285ef4..2a3c641476bd 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>
> >> @@ -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))
> >> @@ -1641,10 +1634,11 @@ 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);
> >> + bool need_mapping = !mr_data->skip_mapping;
> >>
> >> if ( irq < NR_LOCAL_IRQS )
> >> {
> >> @@ -1668,13 +1662,12 @@ 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;
> >> - bool need_mapping = !dt_device_for_passthrough(dev);
> >> + bool need_mapping = !mr_data->skip_mapping;
> >> int res;
> >>
> >> /*
> >> @@ -1726,23 +1719,21 @@ 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;
> >> }
> >> @@ -1823,6 +1814,13 @@ static int __init handle_device(struct domain *d,
> >> struct dt_device_node *dev,
> >> int res;
> >> u64 addr, size;
> >> bool need_mapping = !dt_device_for_passthrough(dev);
> >> + struct map_range_data mr_data = {
> >> + .d = d,
> >> + .p2mt = p2mt,
> >> + .skip_mapping = !need_mapping ||
> >> + (is_pci_passthrough_enabled() &&
> >> + (device_get_class(dev) == DEVICE_PCI))
> >> + };
> > I would prefer if we did this:
> >
> > diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> > index 2a3c641476..1e7cdd11c7 100644
> > --- a/xen/arch/arm/domain_build.c
> > +++ b/xen/arch/arm/domain_build.c
> > @@ -1813,13 +1813,13 @@ 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 need_mapping = !dt_device_for_passthrough(dev) &&
> > + !(is_pci_passthrough_enabled() &&
> > + (device_get_class(dev) == DEVICE_PCI))
> > struct map_range_data mr_data = {
> > .d = d,
> > .p2mt = p2mt,
> > - .skip_mapping = !need_mapping ||
> > - (is_pci_passthrough_enabled() &&
> > - (device_get_class(dev) == DEVICE_PCI))
> > + .skip_mapping = !need_mapping
> > };
> >
> > naddr = dt_number_of_address(dev);
> >
> >
> > This actually makes a difference because otherwise
> > handle_device_interrupts could still be called with need_mapping ==
> > true for PCI devices.
> And this is totally fine. Remember the name of the patch: we do not
> want to map memory, but interrupts are still needed for the bridge to
> function in Dom0. The same as it needs all, but "cfg" from "regs".
> So, need_mapping == true for interrupts is what we want: legacy INTx
> are not supported by design and only MSI/MSI-X are supported.
Ah, makes sense, I momentarily lost sight of that. Could you please add
an in-code comment to explain it, something like:
/*
* For PCI passthrough we need to remap only interrupts to Dom0. MMIO
* regions of the PCIe Root Complex and PCIe aperture should not be
* mapped automatically to Dom0.
*/
struct map_range_data mr_data = {
.d = d,
.p2mt = p2mt,
.skip_mapping = !need_mapping ||
(is_pci_passthrough_enabled() &&
(device_get_class(dev) == DEVICE_PCI))
};
> >
> > What do you think? One more comment below.
> >
> >
> >> naddr = dt_number_of_address(dev);
> >>
> >> @@ -1862,7 +1860,6 @@ 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 };
> >> res = dt_device_get_address(dev, i, &addr, &size);
> >> if ( res )
> >> {
> >> @@ -1876,7 +1873,7 @@ 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;
> >>
> >> @@ -3034,7 +3031,14 @@ 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, 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 602d00799c8d..b81620074a91 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 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 1eb4daa87365..085f08e23e0c 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>
> >> @@ -320,6 +321,54 @@ 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,
> >> + .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" or "assigned-addresses" 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.
> >> + */
> >> + 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 61a9807d3d58..6ad2b31e810d 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 a62d8bc60086..d9a3c2a4f3b3 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_t 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);
> >> int pci_get_host_bridge_segment(const struct dt_device_node *node,
> >> uint16_t *segment);
> >> @@ -113,6 +121,8 @@ int pci_host_iterate_bridges(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*/
> >>
> >> struct arch_pci_dev { };
> >> diff --git a/xen/include/asm-arm/setup.h b/xen/include/asm-arm/setup.h
> >> index 95da0b7ab9cd..5b30135fda38 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. */
> > This comment still needs updating.
> Sorry, I missed this one
> >
> >
> >> + 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:
> >> --
> >> 2.25.1
> >>
>
