[xen stable-4.18] amd-vi: fix IVMD memory type checks

[patchbot@xxxxxxx]

commit fa9950a527a70971bf9279be62d445cf9c83aedf
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Tue Feb 27 13:54:04 2024 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Feb 27 13:54:04 2024 +0100

    amd-vi: fix IVMD memory type checks
    
    The current code that parses the IVMD blocks is relaxed with regard to the
    restriction that such unity regions should always fall into memory ranges
    marked as reserved in the memory map.
    
    However the type checks for the IVMD addresses are inverted, and as a result
    IVMD ranges falling into RAM areas are accepted.  Note that having such 
ranges
    in the first place is a firmware bug, as IVMD should always fall into 
reserved
    ranges.
    
    Fixes: ed6c77ebf0c1 ('AMD/IOMMU: check / convert IVMD ranges for being / to 
be reserved')
    Reported-by: Ox <oxjo@xxxxxxxxx>
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Tested-by: oxjo <oxjo@xxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    master commit: 83afa313583019d9f159c122cecf867735d27ec5
    master date: 2024-02-06 11:56:13 +0100
---
 xen/drivers/passthrough/amd/iommu_acpi.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/xen/drivers/passthrough/amd/iommu_acpi.c 
b/xen/drivers/passthrough/amd/iommu_acpi.c
index 699d33f429..96d8879e7b 100644
--- a/xen/drivers/passthrough/amd/iommu_acpi.c
+++ b/xen/drivers/passthrough/amd/iommu_acpi.c
@@ -426,9 +426,14 @@ static int __init parse_ivmd_block(const struct 
acpi_ivrs_memory *ivmd_block)
                 return -EIO;
             }
 
-            /* Types which won't be handed out are considered good enough. */
-            if ( !(type & (RAM_TYPE_RESERVED | RAM_TYPE_ACPI |
-                           RAM_TYPE_UNUSABLE)) )
+            /*
+             * Types which aren't RAM are considered good enough.
+             * Note that a page being partially RESERVED, ACPI or UNUSABLE will
+             * force Xen into assuming the whole page as having that type in
+             * practice.
+             */
+            if ( type & (RAM_TYPE_RESERVED | RAM_TYPE_ACPI |
+                         RAM_TYPE_UNUSABLE) )
                 continue;
 
             AMD_IOMMU_ERROR("IVMD: page at %lx can't be converted\n", addr);
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.18