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SUSE:SLE-15-SP2:Update
xen.30827
6126344f-AMD-IOMMU-unity-map-handling.patch
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File 6126344f-AMD-IOMMU-unity-map-handling.patch of Package xen.30827
# Commit 34750a3eb022462cdd1c36e8ef9049d3d73c824c # Date 2021-08-25 14:15:11 +0200 # Author Jan Beulich <jbeulich@suse.com> # Committer Jan Beulich <jbeulich@suse.com> AMD/IOMMU: correct device unity map handling Blindly assuming all addresses between any two such ranges, specified by firmware in the ACPI tables, should also be unity-mapped can't be right. Nor can it be correct to merge ranges with differing permissions. Track ranges individually; don't merge at all, but check for overlaps instead. This requires bubbling up error indicators, such that IOMMU init can be failed when allocation of a new tracking struct wasn't possible, or an overlap was detected. At this occasion also stop ignoring amd_iommu_reserve_domain_unity_map()'s return value. This is part of XSA-378 / CVE-2021-28695. Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: George Dunlap <george.dunlap@citrix.com> Reviewed-by: Paul Durrant <paul@xen.org> --- a/xen/drivers/passthrough/amd/iommu_acpi.c +++ b/xen/drivers/passthrough/amd/iommu_acpi.c @@ -127,32 +127,48 @@ static int __init reserve_iommu_exclusio return 0; } -static void __init reserve_unity_map_for_device( - u16 seg, u16 bdf, unsigned long base, - unsigned long length, u8 iw, u8 ir) +static int __init reserve_unity_map_for_device( + uint16_t seg, uint16_t bdf, unsigned long base, + unsigned long length, bool iw, bool ir) { struct ivrs_mappings *ivrs_mappings = get_ivrs_mappings(seg); - unsigned long old_top, new_top; + struct ivrs_unity_map *unity_map = ivrs_mappings[bdf].unity_map; - /* need to extend unity-mapped range? */ - if ( ivrs_mappings[bdf].unity_map_enable ) + /* Check for overlaps. */ + for ( ; unity_map; unity_map = unity_map->next ) { - old_top = ivrs_mappings[bdf].addr_range_start + - ivrs_mappings[bdf].addr_range_length; - new_top = base + length; - if ( old_top > new_top ) - new_top = old_top; - if ( ivrs_mappings[bdf].addr_range_start < base ) - base = ivrs_mappings[bdf].addr_range_start; - length = new_top - base; - } - - /* extend r/w permissioms and keep aggregate */ - ivrs_mappings[bdf].write_permission = iw; - ivrs_mappings[bdf].read_permission = ir; - ivrs_mappings[bdf].unity_map_enable = IOMMU_CONTROL_ENABLED; - ivrs_mappings[bdf].addr_range_start = base; - ivrs_mappings[bdf].addr_range_length = length; + /* + * Exact matches are okay. This can in particular happen when + * register_exclusion_range_for_device() calls here twice for the + * same (s,b,d,f). + */ + if ( base == unity_map->addr && length == unity_map->length && + ir == unity_map->read && iw == unity_map->write ) + return 0; + + if ( unity_map->addr + unity_map->length > base && + base + length > unity_map->addr ) + { + AMD_IOMMU_DEBUG("IVMD Error: overlap [%lx,%lx) vs [%lx,%lx)\n", + base, base + length, unity_map->addr, + unity_map->addr + unity_map->length); + return -EPERM; + } + } + + /* Populate and insert a new unity map. */ + unity_map = xmalloc(struct ivrs_unity_map); + if ( !unity_map ) + return -ENOMEM; + + unity_map->read = ir; + unity_map->write = iw; + unity_map->addr = base; + unity_map->length = length; + unity_map->next = ivrs_mappings[bdf].unity_map; + ivrs_mappings[bdf].unity_map = unity_map; + + return 0; } static int __init register_exclusion_range_for_all_devices( @@ -175,13 +191,13 @@ static int __init register_exclusion_ran length = range_top - base; /* reserve r/w unity-mapped page entries for devices */ /* note: these entries are part of the exclusion range */ - for ( bdf = 0; bdf < ivrs_bdf_entries; bdf++ ) - reserve_unity_map_for_device(seg, bdf, base, length, iw, ir); + for ( bdf = 0; !rc && bdf < ivrs_bdf_entries; bdf++ ) + rc = reserve_unity_map_for_device(seg, bdf, base, length, iw, ir); /* push 'base' just outside of virtual address space */ base = iommu_top; } /* register IOMMU exclusion range settings */ - if ( limit >= iommu_top ) + if ( !rc && limit >= iommu_top ) { for_each_amd_iommu( iommu ) { @@ -223,15 +239,15 @@ static int __init register_exclusion_ran length = range_top - base; /* reserve unity-mapped page entries for device */ /* note: these entries are part of the exclusion range */ - reserve_unity_map_for_device(seg, bdf, base, length, iw, ir); - reserve_unity_map_for_device(seg, req, base, length, iw, ir); + rc = reserve_unity_map_for_device(seg, bdf, base, length, iw, ir) ?: + reserve_unity_map_for_device(seg, req, base, length, iw, ir); /* push 'base' just outside of virtual address space */ base = iommu_top; } /* register IOMMU exclusion range settings for device */ - if ( limit >= iommu_top ) + if ( !rc && limit >= iommu_top ) { rc = reserve_iommu_exclusion_range(iommu, base, limit, false /* all */, iw, ir); @@ -262,15 +278,15 @@ static int __init register_exclusion_ran length = range_top - base; /* reserve r/w unity-mapped page entries for devices */ /* note: these entries are part of the exclusion range */ - for ( bdf = 0; bdf < ivrs_bdf_entries; bdf++ ) + for ( bdf = 0; !rc && bdf < ivrs_bdf_entries; bdf++ ) { if ( iommu == find_iommu_for_device(iommu->seg, bdf) ) { - reserve_unity_map_for_device(iommu->seg, bdf, base, length, - iw, ir); req = get_ivrs_mappings(iommu->seg)[bdf].dte_requestor_id; - reserve_unity_map_for_device(iommu->seg, req, base, length, - iw, ir); + rc = reserve_unity_map_for_device(iommu->seg, bdf, base, length, + iw, ir) ?: + reserve_unity_map_for_device(iommu->seg, req, base, length, + iw, ir); } } @@ -279,7 +295,7 @@ static int __init register_exclusion_ran } /* register IOMMU exclusion range settings */ - if ( limit >= iommu_top ) + if ( !rc && limit >= iommu_top ) rc = reserve_iommu_exclusion_range(iommu, base, limit, true /* all */, iw, ir); --- a/xen/drivers/passthrough/amd/iommu_init.c +++ b/xen/drivers/passthrough/amd/iommu_init.c @@ -1189,7 +1189,6 @@ static int __init alloc_ivrs_mappings(u1 { ivrs_mappings[bdf].dte_requestor_id = bdf; ivrs_mappings[bdf].dte_allow_exclusion = IOMMU_CONTROL_DISABLED; - ivrs_mappings[bdf].unity_map_enable = IOMMU_CONTROL_DISABLED; ivrs_mappings[bdf].iommu = NULL; ivrs_mappings[bdf].intremap_table = NULL; --- a/xen/drivers/passthrough/amd/pci_amd_iommu.c +++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c @@ -346,15 +346,17 @@ static int amd_iommu_assign_device(struc struct ivrs_mappings *ivrs_mappings = get_ivrs_mappings(pdev->seg); int bdf = PCI_BDF2(pdev->bus, devfn); int req_id = get_dma_requestor_id(pdev->seg, bdf); + const struct ivrs_unity_map *unity_map; - if ( ivrs_mappings[req_id].unity_map_enable ) + for ( unity_map = ivrs_mappings[req_id].unity_map; unity_map; + unity_map = unity_map->next ) { - amd_iommu_reserve_domain_unity_map( - d, - ivrs_mappings[req_id].addr_range_start, - ivrs_mappings[req_id].addr_range_length, - ivrs_mappings[req_id].write_permission, - ivrs_mappings[req_id].read_permission); + int rc = amd_iommu_reserve_domain_unity_map( + d, unity_map->addr, unity_map->length, + unity_map->write, unity_map->read); + + if ( rc ) + return rc; } return reassign_device(pdev->domain, d, devfn, pdev); --- a/xen/include/asm-x86/amd-iommu.h +++ b/xen/include/asm-x86/amd-iommu.h @@ -108,15 +108,19 @@ struct amd_iommu { struct list_head ats_devices; }; +struct ivrs_unity_map { + bool read:1; + bool write:1; + paddr_t addr; + unsigned long length; + struct ivrs_unity_map *next; +}; + struct ivrs_mappings { u16 dte_requestor_id; u8 dte_allow_exclusion; - u8 unity_map_enable; - u8 write_permission; - u8 read_permission; - unsigned long addr_range_start; - unsigned long addr_range_length; struct amd_iommu *iommu; + struct ivrs_unity_map *unity_map; /* per device interrupt remapping table */ void *intremap_table;
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