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

[Rahul Singh <Rahul.Singh@xxxxxxx>]

Hi Stefano,

> On 5 Oct 2021, at 1:38 am, Stefano Stabellini <sstabellini@xxxxxxxxxx> wrote:
> 
> 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@xxxxxxx>
>> ---
>> 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.

Yes make sense I will add the pci_cleanup_msi(pdev) in next version.

Regards,
Rahul
> 
> With that:
> 
> Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> 
> 
> 
>> +        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