Re: [PATCH v4 11/14] xen/arm: Enable the existing x86 virtual PCI support for ARM.

[Stefano Stabellini <sstabellini@kernel.org>]

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On Mon, 4 Oct 2021, Rahul Singh wrote:
> The existing VPCI support available for X86 is adapted for Arm.
> When the device is added to XEN via the hyper call
> “PHYSDEVOP_pci_device_add”, VPCI handler for the config space
> access is added to the Xen to emulate the PCI devices config space.
> 
> A MMIO trap handler for the PCI ECAM space is registered in XEN
> so that when guest is trying to access the PCI config space,XEN
> will trap the access and emulate read/write using the VPCI and
> not the real PCI hardware.
> 
> For Dom0less systems scan_pci_devices() would be used to discover the
> PCI device in XEN and VPCI handler will be added during XEN boots.
> 
> Signed-off-by: Rahul Singh <rahul.singh@arm.com>
> ---
> Change in v4:
> - Move addition of XEN_DOMCTL_CDF_vpci flag to separate patch
> Change in v3:
> - Use is_pci_passthrough_enabled() in place of pci_passthrough_enabled variable
> - Reject XEN_DOMCTL_CDF_vpci for x86 in arch_sanitise_domain_config()
> - Remove IS_ENABLED(CONFIG_HAS_VPCI) from has_vpci()
> Change in v2:
> - Add new XEN_DOMCTL_CDF_vpci flag
> - modify has_vpci() to include XEN_DOMCTL_CDF_vpci
> - enable vpci support when pci-passthough option is enabled.
> ---
> ---
>  xen/arch/arm/Makefile         |   1 +
>  xen/arch/arm/domain.c         |   4 ++
>  xen/arch/arm/domain_build.c   |   3 +
>  xen/arch/arm/vpci.c           | 102 ++++++++++++++++++++++++++++++++++
>  xen/arch/arm/vpci.h           |  36 ++++++++++++
>  xen/drivers/passthrough/pci.c |  17 ++++++
>  xen/include/asm-arm/domain.h  |   7 ++-
>  xen/include/asm-x86/pci.h     |   2 -
>  xen/include/public/arch-arm.h |   7 +++
>  xen/include/xen/pci.h         |   2 +
>  10 files changed, 178 insertions(+), 3 deletions(-)
>  create mode 100644 xen/arch/arm/vpci.c
>  create mode 100644 xen/arch/arm/vpci.h
> 
> diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
> index 44d7cc81fa..fb9c976ea2 100644
> --- a/xen/arch/arm/Makefile
> +++ b/xen/arch/arm/Makefile
> @@ -7,6 +7,7 @@ ifneq ($(CONFIG_NO_PLAT),y)
>  obj-y += platforms/
>  endif
>  obj-$(CONFIG_TEE) += tee/
> +obj-$(CONFIG_HAS_VPCI) += vpci.o
>  
>  obj-$(CONFIG_HAS_ALTERNATIVE) += alternative.o
>  obj-y += bootfdt.init.o
> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> index 36138c1b2e..fbb52f78f1 100644
> --- a/xen/arch/arm/domain.c
> +++ b/xen/arch/arm/domain.c
> @@ -39,6 +39,7 @@
>  #include <asm/vgic.h>
>  #include <asm/vtimer.h>
>  
> +#include "vpci.h"
>  #include "vuart.h"
>  
>  DEFINE_PER_CPU(struct vcpu *, curr_vcpu);
> @@ -767,6 +768,9 @@ int arch_domain_create(struct domain *d,
>      if ( is_hardware_domain(d) && (rc = domain_vuart_init(d)) )
>          goto fail;
>  
> +    if ( (rc = domain_vpci_init(d)) != 0 )
> +        goto fail;
> +
>      return 0;
>  
>  fail:
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index c5afbe2e05..f4c89bde8c 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -3053,6 +3053,9 @@ void __init create_dom0(void)
>      if ( iommu_enabled )
>          dom0_cfg.flags |= XEN_DOMCTL_CDF_iommu;
>  
> +    if ( is_pci_passthrough_enabled() )
> +        dom0_cfg.flags |= XEN_DOMCTL_CDF_vpci;
> +
>      dom0 = domain_create(0, &dom0_cfg, true);
>      if ( IS_ERR(dom0) || (alloc_dom0_vcpu0(dom0) == NULL) )
>          panic("Error creating domain 0\n");
> diff --git a/xen/arch/arm/vpci.c b/xen/arch/arm/vpci.c
> new file mode 100644
> index 0000000000..76c12b9281
> --- /dev/null
> +++ b/xen/arch/arm/vpci.c
> @@ -0,0 +1,102 @@
> +/*
> + * xen/arch/arm/vpci.c
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +#include <xen/sched.h>
> +
> +#include <asm/mmio.h>
> +
> +#define REGISTER_OFFSET(addr)  ( (addr) & 0x00000fff)
> +
> +/* Do some sanity checks. */
> +static bool vpci_mmio_access_allowed(unsigned int reg, unsigned int len)
> +{
> +    /* Check access size. */
> +    if ( len > 8 )
> +        return false;
> +
> +    /* Check that access is size aligned. */
> +    if ( (reg & (len - 1)) )
> +        return false;
> +
> +    return true;
> +}
> +
> +static int vpci_mmio_read(struct vcpu *v, mmio_info_t *info,
> +                          register_t *r, void *p)
> +{
> +    unsigned int reg;
> +    pci_sbdf_t sbdf;
> +    unsigned long data = ~0UL;
> +    unsigned int size = 1U << info->dabt.size;
> +
> +    sbdf.sbdf = MMCFG_BDF(info->gpa);
> +    reg = REGISTER_OFFSET(info->gpa);
> +
> +    if ( !vpci_mmio_access_allowed(reg, size) )
> +        return 0;
> +
> +    data = vpci_read(sbdf, reg, min(4u, size));
> +    if ( size == 8 )
> +        data |= (uint64_t)vpci_read(sbdf, reg + 4, 4) << 32;
> +
> +    *r = data;
> +
> +    return 1;
> +}
> +
> +static int vpci_mmio_write(struct vcpu *v, mmio_info_t *info,
> +                           register_t r, void *p)
> +{
> +    unsigned int reg;
> +    pci_sbdf_t sbdf;
> +    unsigned long data = r;
> +    unsigned int size = 1U << info->dabt.size;
> +
> +    sbdf.sbdf = MMCFG_BDF(info->gpa);
> +    reg = REGISTER_OFFSET(info->gpa);
> +
> +    if ( !vpci_mmio_access_allowed(reg, size) )
> +        return 0;
> +
> +    vpci_write(sbdf, reg, min(4u, size), data);
> +    if ( size == 8 )
> +        vpci_write(sbdf, reg + 4, 4, data >> 32);
> +
> +    return 1;
> +}
> +
> +static const struct mmio_handler_ops vpci_mmio_handler = {
> +    .read  = vpci_mmio_read,
> +    .write = vpci_mmio_write,
> +};
> +
> +int domain_vpci_init(struct domain *d)
> +{
> +    if ( !has_vpci(d) )
> +        return 0;
> +
> +    register_mmio_handler(d, &vpci_mmio_handler,
> +                          GUEST_VPCI_ECAM_BASE, GUEST_VPCI_ECAM_SIZE, NULL);
> +
> +    return 0;
> +}
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> +
> diff --git a/xen/arch/arm/vpci.h b/xen/arch/arm/vpci.h
> new file mode 100644
> index 0000000000..d8a7b0e3e8
> --- /dev/null
> +++ b/xen/arch/arm/vpci.h
> @@ -0,0 +1,36 @@
> +/*
> + * xen/arch/arm/vpci.h
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef __ARCH_ARM_VPCI_H__
> +#define __ARCH_ARM_VPCI_H__
> +
> +#ifdef CONFIG_HAS_VPCI
> +int domain_vpci_init(struct domain *d);
> +#else
> +static inline int domain_vpci_init(struct domain *d)
> +{
> +    return 0;
> +}
> +#endif
> +
> +#endif /* __ARCH_ARM_VPCI_H__ */
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
> index e1b735d9e8..b36d5a4811 100644
> --- a/xen/drivers/passthrough/pci.c
> +++ b/xen/drivers/passthrough/pci.c
> @@ -766,6 +766,23 @@ int pci_add_device(u16 seg, u8 bus, u8 devfn,
>      else
>          iommu_enable_device(pdev);
>  
> +#ifdef CONFIG_ARM
> +    /*
> +     * On ARM PCI devices discovery will be done by Dom0. Add vpci handler when
> +     * Dom0 inform XEN to add the PCI devices in XEN.
> +     */
> +    ret = vpci_add_handlers(pdev);
> +    if ( ret )
> +    {
> +        printk(XENLOG_ERR "setup of vPCI failed: %d\n", ret);

I would also call:

  pci_cleanup_msi(pdev);


I know it does nothing on ARM today, but it serves as a reminder that in
the future likely MSIs will have to be cleaned up here.

With that:

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>



> +        ret = iommu_remove_device(pdev);
> +        if ( pdev->domain )
> +            list_del(&pdev->domain_list);
> +        free_pdev(pseg, pdev);
> +        goto out;
> +    }
> +#endif
> +
>      pci_enable_acs(pdev);
>  
>  out:
> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> index c9277b5c6d..91d614b37e 100644
> --- a/xen/include/asm-arm/domain.h
> +++ b/xen/include/asm-arm/domain.h
> @@ -2,6 +2,7 @@
>  #define __ASM_DOMAIN_H__
>  
>  #include <xen/cache.h>
> +#include <xen/nospec.h>
>  #include <xen/timer.h>
>  #include <asm/page.h>
>  #include <asm/p2m.h>
> @@ -262,7 +263,11 @@ static inline void arch_vcpu_block(struct vcpu *v) {}
>  
>  #define arch_vm_assist_valid_mask(d) (1UL << VMASST_TYPE_runstate_update_flag)
>  
> -#define has_vpci(d)    ({ (void)(d); false; })
> +/*
> + * For X86 VPCI is enabled and tested for PVH DOM0 only but
> + * for ARM we enable support VPCI for guest domain also.
> + */
> +#define has_vpci(d) evaluate_nospec((d)->options & XEN_DOMCTL_CDF_vpci)
>  
>  #endif /* __ASM_DOMAIN_H__ */
>  
> diff --git a/xen/include/asm-x86/pci.h b/xen/include/asm-x86/pci.h
> index e076951032..c4a4fdcbc2 100644
> --- a/xen/include/asm-x86/pci.h
> +++ b/xen/include/asm-x86/pci.h
> @@ -6,8 +6,6 @@
>  #define CF8_ADDR_HI(cf8) (  ((cf8) & 0x0f000000) >> 16)
>  #define CF8_ENABLED(cf8) (!!((cf8) & 0x80000000))
>  
> -#define MMCFG_BDF(addr)  ( ((addr) & 0x0ffff000) >> 12)
> -
>  #define IS_SNB_GFX(id) (id == 0x01068086 || id == 0x01168086 \
>                          || id == 0x01268086 || id == 0x01028086 \
>                          || id == 0x01128086 || id == 0x01228086 \
> diff --git a/xen/include/public/arch-arm.h b/xen/include/public/arch-arm.h
> index d46c61fca9..44be337dec 100644
> --- a/xen/include/public/arch-arm.h
> +++ b/xen/include/public/arch-arm.h
> @@ -418,6 +418,13 @@ typedef uint64_t xen_callback_t;
>  #define GUEST_GICV3_GICR0_BASE     xen_mk_ullong(0x03020000) /* vCPU0..127 */
>  #define GUEST_GICV3_GICR0_SIZE     xen_mk_ullong(0x01000000)
>  
> +/*
> + * 256 MB is reserved for VPCI configuration space based on calculation
> + * 256 buses × 32 devices × 8 functions × 4 KB = 256 MB
> + */
> +#define GUEST_VPCI_ECAM_BASE    xen_mk_ullong(0x10000000)
> +#define GUEST_VPCI_ECAM_SIZE    xen_mk_ullong(0x10000000)
> +
>  /* ACPI tables physical address */
>  #define GUEST_ACPI_BASE xen_mk_ullong(0x20000000)
>  #define GUEST_ACPI_SIZE xen_mk_ullong(0x02000000)
> diff --git a/xen/include/xen/pci.h b/xen/include/xen/pci.h
> index 70ac25345c..43b8a08170 100644
> --- a/xen/include/xen/pci.h
> +++ b/xen/include/xen/pci.h
> @@ -40,6 +40,8 @@
>  #define PCI_SBDF3(s,b,df) \
>      ((pci_sbdf_t){ .sbdf = (((s) & 0xffff) << 16) | PCI_BDF2(b, df) })
>  
> +#define MMCFG_BDF(addr)  (((addr) & 0x0ffff000) >> 12)
> +
>  typedef union {
>      uint32_t sbdf;
>      struct {
> -- 
> 2.25.1
>