Re: [Xen-devel] [PATCH v7 6/6] x86/iommu: add map-reserved dom0-iommu option to map reserved memory ranges

[Julien Grall <julien.grall@xxxxxxx>]

Hi Roger,

On 22/08/18 08:52, Roger Pau Monne wrote:
> Several people have reported hardware issues (malfunctioning USB
> controllers) due to iommu page faults on Intel hardware. Those faults
> are caused by missing RMRR (VTd) entries in the ACPI tables. Those can
> be worked around on VTd hardware by manually adding RMRR entries on
> the command line, this is however limited to Intel hardware and quite
> cumbersome to do.
>
> In order to solve those issues add a new dom0-iommu=map-reserved
> option that identity maps all regions marked as reserved in the memory
> map. Note that regions used by devices emulated by Xen (LAPIC, IO-APIC
> or PCIe MCFG regions) are specifically avoided. Note that this option
> is available to all Dom0 modes (as opposed to the inclusive option
> which only works for PV Dom0).
>
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> ---
> Changes since v6:
>   - Reword the map-reserved help to make it clear it's available to
>     both PV and PVH Dom0.
>   - Assign type inside of the switch expression.
>   - Remove the comment about IO-APIC MMIO relocation, this is not
>     supported ATM.
>
> Changes since v5:
>   - Merge with the vpci MMCFG helper patch.
>   - Add a TODO item about the issues with relocating the LAPIC or
>     IOAPIC MMIO regions.
>   - Use the newly introduced page_get_ram_type that returns all the
>     types that fall between a page.
>   - Use paging_mode_translate instead of iommu_use_hap_pt when deciding
>     whether to use set_identity_p2m_entry or iommu_map_page.
>
> Changes since v4:
>   - Use pfn_to_paddr.
>   - Rebase on top of previous changes.
>   - Change the default option setting to use if instead of a ternary
>     operator.
>   - Rename to map-reserved.
>
> Changes since v3:
>   - Add mappings if the iommu page tables are shared.
>
> Changes since v2:
>   - Fix comment regarding dom0-strict.
>   - Change documentation style of xen command line.
>   - Rename iommu_map to hwdom_iommu_map.
>   - Move all the checks to hwdom_iommu_map.
>
> Changes since v1:
>   - Introduce a new reserved option instead of abusing the inclusive
>     option.
>   - Use the same helper function for PV and PVH in order to decide if a
>     page should be added to the domain page tables.
>   - Use the data inside of the domain struct to detect overlaps with
>     emulated MMIO regions.
> ---
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxx>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Tim Deegan <tim@xxxxxxx>
> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
> Cc: Paul Durrant <paul.durrant@xxxxxxxxxx>
> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
> Cc: Brian Woods <brian.woods@xxxxxxx>
> Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> ---
>   docs/misc/xen-command-line.markdown         |  9 ++++
>   xen/arch/x86/hvm/io.c                       |  5 ++
>   xen/drivers/passthrough/amd/pci_amd_iommu.c |  3 ++
>   xen/drivers/passthrough/arm/smmu.c          |  1 +
>   xen/drivers/passthrough/iommu.c             |  3 ++
>   xen/drivers/passthrough/vtd/iommu.c         |  3 ++
>   xen/drivers/passthrough/x86/iommu.c         | 53 ++++++++++++++++++---
>   xen/include/asm-x86/hvm/io.h                |  3 ++
>   xen/include/xen/iommu.h                     |  2 +-
>   9 files changed, 75 insertions(+), 7 deletions(-)
>
> diff --git a/docs/misc/xen-command-line.markdown 
> b/docs/misc/xen-command-line.markdown
> index 98f0f3b68b..1ffd586224 100644
> --- a/docs/misc/xen-command-line.markdown
> +++ b/docs/misc/xen-command-line.markdown
> @@ -704,6 +704,15 @@ This list of booleans controls the iommu usage by Dom0:
>     option is only applicable to a PV Dom0 and is enabled by default on Intel
>     hardware.
>   
> +* `map-reserved`: sets up DMA remapping for all the reserved regions in the
> +  memory map for Dom0. Use this to work around firmware issues providing
> +  incorrect RMRR/IVMD entries. Rather than only mapping RAM pages for IOMMU
> +  accesses for Dom0, all memory regions marked as reserved in the memory map
> +  that don't overlap with any MMIO region from emulated devices will be
> +  identity mapped. This option maps a subset of the memory that would be
> +  mapped when using the `map-inclusive` option. This option is available to all
> +  Dom0 modes and is enabled by default on Intel hardware.
> +
>   ### dom0\_ioports\_disable (x86)
>   > `= List of <hex>-<hex>`
>   
> diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
> index bf4d8748d3..1f8fe36168 100644
> --- a/xen/arch/x86/hvm/io.c
> +++ b/xen/arch/x86/hvm/io.c
> @@ -404,6 +404,11 @@ static const struct hvm_mmcfg *vpci_mmcfg_find(const 
> struct domain *d,
>       return NULL;
>   }
>   
> +bool vpci_is_mmcfg_address(const struct domain *d, paddr_t addr)
> +{
> +    return vpci_mmcfg_find(d, addr);
> +}
> +
>   static unsigned int vpci_mmcfg_decode_addr(const struct hvm_mmcfg *mmcfg,
>                                              paddr_t addr, pci_sbdf_t *sbdf)
>   {
> diff --git a/xen/drivers/passthrough/amd/pci_amd_iommu.c 
> b/xen/drivers/passthrough/amd/pci_amd_iommu.c
> index 27eb49619d..49d934e1ac 100644
> --- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
> +++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
> @@ -256,6 +256,9 @@ static void __hwdom_init amd_iommu_hwdom_init(struct domain 
> *d)
>       /* Inclusive IOMMU mappings are disabled by default on AMD hardware. */
>       if ( iommu_hwdom_inclusive == -1 )
>           iommu_hwdom_inclusive = false;
> +    /* Reserved IOMMU mappings are disabled by default on AMD hardware. */
> +    if ( iommu_hwdom_reserved == -1 )
> +        iommu_hwdom_reserved = false;
Same as patch #1, you are mixing boolean and integer.

Cheers,

--
Julien Grall

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