RE: [PATCH v4 11/14] iommu: stop calling IOMMU page tables 'p2m tables'

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Paul Durrant <paul@xxxxxxx>
> Sent: Tuesday, August 4, 2020 9:42 PM
> 
> From: Paul Durrant <pdurrant@xxxxxxxxxx>
> 
> It's confusing and not consistent with the terminology introduced with 
> 'dfn_t'.
> Just call them IOMMU page tables.
> 
> Also remove a pointless check of the 'acpi_drhd_units' list in
> vtd_dump_page_table_level(). If the list is empty then IOMMU mappings
> would
> not have been enabled for the domain in the first place.
> 
> NOTE: All calls to printk() have also been removed from
>       iommu_dump_page_tables(); the implementation specific code is now
>       responsible for all output.
>       The check for the global 'iommu_enabled' has also been replaced by an
>       ASSERT since iommu_dump_page_tables() is not registered as a key
> handler
>       unless IOMMU mappings are enabled.
> 
> Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>

with Jan's comments addressed:
        Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>

> ---
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: Paul Durrant <paul@xxxxxxx>
> Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> 
> v2:
>  - Moved all output into implementation specific code
> ---
>  xen/drivers/passthrough/amd/pci_amd_iommu.c | 16 ++++++-------
>  xen/drivers/passthrough/iommu.c             | 21 ++++-------------
>  xen/drivers/passthrough/vtd/iommu.c         | 26 +++++++++++----------
>  xen/include/xen/iommu.h                     |  2 +-
>  4 files changed, 28 insertions(+), 37 deletions(-)
> 
> diff --git a/xen/drivers/passthrough/amd/pci_amd_iommu.c
> b/xen/drivers/passthrough/amd/pci_amd_iommu.c
> index 3390c22cf3..be578607b1 100644
> --- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
> +++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
> @@ -491,8 +491,8 @@ static int amd_iommu_group_id(u16 seg, u8 bus, u8
> devfn)
> 
>  #include <asm/io_apic.h>
> 
> -static void amd_dump_p2m_table_level(struct page_info* pg, int level,
> -                                     paddr_t gpa, int indent)
> +static void amd_dump_page_table_level(struct page_info* pg, int level,
> +                                      paddr_t gpa, int indent)
>  {
>      paddr_t address;
>      struct amd_iommu_pte *table_vaddr;
> @@ -529,7 +529,7 @@ static void amd_dump_p2m_table_level(struct
> page_info* pg, int level,
> 
>          address = gpa + amd_offset_level_address(index, level);
>          if ( pde->next_level >= 1 )
> -            amd_dump_p2m_table_level(
> +            amd_dump_page_table_level(
>                  mfn_to_page(_mfn(pde->mfn)), pde->next_level,
>                  address, indent + 1);
>          else
> @@ -542,16 +542,16 @@ static void amd_dump_p2m_table_level(struct
> page_info* pg, int level,
>      unmap_domain_page(table_vaddr);
>  }
> 
> -static void amd_dump_p2m_table(struct domain *d)
> +static void amd_dump_page_tables(struct domain *d)
>  {
>      const struct domain_iommu *hd = dom_iommu(d);
> 
>      if ( !hd->arch.amd.root_table )
>          return;
> 
> -    printk("p2m table has %u levels\n", hd->arch.amd.paging_mode);
> -    amd_dump_p2m_table_level(hd->arch.amd.root_table,
> -                             hd->arch.amd.paging_mode, 0, 0);
> +    printk("AMD IOMMU table has %u levels\n", hd-
> >arch.amd.paging_mode);
> +    amd_dump_page_table_level(hd->arch.amd.root_table,
> +                              hd->arch.amd.paging_mode, 0, 0);
>  }
> 
>  static const struct iommu_ops __initconstrel _iommu_ops = {
> @@ -578,7 +578,7 @@ static const struct iommu_ops __initconstrel
> _iommu_ops = {
>      .suspend = amd_iommu_suspend,
>      .resume = amd_iommu_resume,
>      .crash_shutdown = amd_iommu_crash_shutdown,
> -    .dump_p2m_table = amd_dump_p2m_table,
> +    .dump_page_tables = amd_dump_page_tables,
>  };
> 
>  static const struct iommu_init_ops __initconstrel _iommu_init_ops = {
> diff --git a/xen/drivers/passthrough/iommu.c
> b/xen/drivers/passthrough/iommu.c
> index 7464f10d1c..0f468379e1 100644
> --- a/xen/drivers/passthrough/iommu.c
> +++ b/xen/drivers/passthrough/iommu.c
> @@ -22,7 +22,7 @@
>  #include <xen/keyhandler.h>
>  #include <xsm/xsm.h>
> 
> -static void iommu_dump_p2m_table(unsigned char key);
> +static void iommu_dump_page_tables(unsigned char key);
> 
>  unsigned int __read_mostly iommu_dev_iotlb_timeout = 1000;
>  integer_param("iommu_dev_iotlb_timeout", iommu_dev_iotlb_timeout);
> @@ -212,7 +212,7 @@ void __hwdom_init iommu_hwdom_init(struct
> domain *d)
>      if ( !is_iommu_enabled(d) )
>          return;
> 
> -    register_keyhandler('o', &iommu_dump_p2m_table, "dump iommu p2m
> table", 0);
> +    register_keyhandler('o', &iommu_dump_page_tables, "dump iommu
> page tables", 0);
> 
>      hd->platform_ops->hwdom_init(d);
>  }
> @@ -533,16 +533,12 @@ bool_t iommu_has_feature(struct domain *d,
> enum iommu_feature feature)
>      return is_iommu_enabled(d) && test_bit(feature, dom_iommu(d)-
> >features);
>  }
> 
> -static void iommu_dump_p2m_table(unsigned char key)
> +static void iommu_dump_page_tables(unsigned char key)
>  {
>      struct domain *d;
>      const struct iommu_ops *ops;
> 
> -    if ( !iommu_enabled )
> -    {
> -        printk("IOMMU not enabled!\n");
> -        return;
> -    }
> +    ASSERT(iommu_enabled);
> 
>      ops = iommu_get_ops();
> 
> @@ -553,14 +549,7 @@ static void iommu_dump_p2m_table(unsigned char
> key)
>          if ( is_hardware_domain(d) || !is_iommu_enabled(d) )
>              continue;
> 
> -        if ( iommu_use_hap_pt(d) )
> -        {
> -            printk("\ndomain%d IOMMU p2m table shared with MMU: \n", d-
> >domain_id);
> -            continue;
> -        }
> -
> -        printk("\ndomain%d IOMMU p2m table: \n", d->domain_id);
> -        ops->dump_p2m_table(d);
> +        ops->dump_page_tables(d);
>      }
> 
>      rcu_read_unlock(&domlist_read_lock);
> diff --git a/xen/drivers/passthrough/vtd/iommu.c
> b/xen/drivers/passthrough/vtd/iommu.c
> index a532d9e88c..f8da4fe0e7 100644
> --- a/xen/drivers/passthrough/vtd/iommu.c
> +++ b/xen/drivers/passthrough/vtd/iommu.c
> @@ -2582,8 +2582,8 @@ static void vtd_resume(void)
>      }
>  }
> 
> -static void vtd_dump_p2m_table_level(paddr_t pt_maddr, int level, paddr_t
> gpa,
> -                                     int indent)
> +static void vtd_dump_page_table_level(paddr_t pt_maddr, int level,
> paddr_t gpa,
> +                                      int indent)
>  {
>      paddr_t address;
>      int i;
> @@ -2612,8 +2612,8 @@ static void vtd_dump_p2m_table_level(paddr_t
> pt_maddr, int level, paddr_t gpa,
> 
>          address = gpa + offset_level_address(i, level);
>          if ( next_level >= 1 )
> -            vtd_dump_p2m_table_level(dma_pte_addr(*pte), next_level,
> -                                     address, indent + 1);
> +            vtd_dump_page_table_level(dma_pte_addr(*pte), next_level,
> +                                      address, indent + 1);
>          else
>              printk("%*sdfn: %08lx mfn: %08lx\n",
>                     indent, "",
> @@ -2624,17 +2624,19 @@ static void vtd_dump_p2m_table_level(paddr_t
> pt_maddr, int level, paddr_t gpa,
>      unmap_vtd_domain_page(pt_vaddr);
>  }
> 
> -static void vtd_dump_p2m_table(struct domain *d)
> +static void vtd_dump_page_tables(struct domain *d)
>  {
> -    const struct domain_iommu *hd;
> +    const struct domain_iommu *hd = dom_iommu(d);
> 
> -    if ( list_empty(&acpi_drhd_units) )
> +    if ( iommu_use_hap_pt(d) )
> +    {
> +        printk("VT-D sharing EPT table\n");
>          return;
> +    }
> 
> -    hd = dom_iommu(d);
> -    printk("p2m table has %d levels\n", agaw_to_level(hd->arch.vtd.agaw));
> -    vtd_dump_p2m_table_level(hd->arch.vtd.pgd_maddr,
> -                             agaw_to_level(hd->arch.vtd.agaw), 0, 0);
> +    printk("VT-D table has %d levels\n", agaw_to_level(hd->arch.vtd.agaw));
> +    vtd_dump_page_table_level(hd->arch.vtd.pgd_maddr,
> +                              agaw_to_level(hd->arch.vtd.agaw), 0, 0);
>  }
> 
>  static int __init intel_iommu_quarantine_init(struct domain *d)
> @@ -2734,7 +2736,7 @@ static struct iommu_ops __initdata vtd_ops = {
>      .iotlb_flush = iommu_flush_iotlb_pages,
>      .iotlb_flush_all = iommu_flush_iotlb_all,
>      .get_reserved_device_memory =
> intel_iommu_get_reserved_device_memory,
> -    .dump_p2m_table = vtd_dump_p2m_table,
> +    .dump_page_tables = vtd_dump_page_tables,
>  };
> 
>  const struct iommu_init_ops __initconstrel intel_iommu_init_ops = {
> diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
> index 1f25d2082f..23e884f54b 100644
> --- a/xen/include/xen/iommu.h
> +++ b/xen/include/xen/iommu.h
> @@ -277,7 +277,7 @@ struct iommu_ops {
>                                      unsigned int flush_flags);
>      int __must_check (*iotlb_flush_all)(struct domain *d);
>      int (*get_reserved_device_memory)(iommu_grdm_t *, void *);
> -    void (*dump_p2m_table)(struct domain *d);
> +    void (*dump_page_tables)(struct domain *d);
> 
>  #ifdef CONFIG_HAS_DEVICE_TREE
>      /*
> --
> 2.20.1