On Wed, 6 Oct 2021, Oleksandr Andrushchenko wrote:
> On 06.10.21 00:43, Stefano Stabellini wrote:
> > 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://urldefense.com/v3/__https://lists.xenproject.org/archives/html/xen-devel/2020-07/msg00777.html__;!!GF_29dbcQIUBPA!nW_LVc5NeS7QQII7CDO4h3ifHhxdPAvQpLSVaX1CRyXh3c1a4a9cBpQ9S7SiAsDdMbL5RkTJpw$
> >>>> [lists[.]xenproject[.]org]
> >>>> [2]
> >>>> https://urldefense.com/v3/__https://www.kernel.org/doc/Documentation/devicetree/bindings/pci/host-generic-pci.txt__;!!GF_29dbcQIUBPA!nW_LVc5NeS7QQII7CDO4h3ifHhxdPAvQpLSVaX1CRyXh3c1a4a9cBpQ9S7SiAsDdMbL-vGunhg$
> >>>> [kernel[.]org]
> >>>> [3]
> >>>> https://urldefense.com/v3/__https://www.kernel.org/doc/Documentation/devicetree/bindings/pci/hisilicon-pcie.txt__;!!GF_29dbcQIUBPA!nW_LVc5NeS7QQII7CDO4h3ifHhxdPAvQpLSVaX1CRyXh3c1a4a9cBpQ9S7SiAsDdMbKjL04tRA$
> >>>> [kernel[.]org]
> >>>>
> >>>> 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))
> > };
> Sure will add this so we don't step on it in the future.
> Other than this and the missed comment below do you think
> that patch is good to go now?
Yes, I think it is good to go. I plan to add my reviewed-by next time
just to double-check that everything is as expected.
> >>> 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
> >>>>
>
