[xen stable-4.13] x86/vtd: relax EPT page table sharing check

[patchbot@xxxxxxx]

commit c8986e990c91cdda89e57c71293ed0c424e4e474
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Mon Apr 27 15:02:08 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Apr 27 15:02:08 2020 +0200

    x86/vtd: relax EPT page table sharing check
    
    The EPT page tables can be shared with the IOMMU as long as the page
    sizes supported by EPT are also supported by the IOMMU.
    
    Current code checks that both the IOMMU and EPT support the same page
    sizes, but this is not strictly required, the IOMMU supporting more
    page sizes than EPT is fine and shouldn't block page table sharing.
    
    This is likely not a common case (IOMMU supporting more page sizes
    than EPT), but should still be fixed for correctness.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
    master commit: 3957e12c02670b97855ef0933b373f99993fa598
    master date: 2020-04-21 10:54:56 +0200
---
 xen/drivers/passthrough/vtd/iommu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index 1a239447ac..26401c7e64 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1911,8 +1911,8 @@ static int __init vtd_ept_page_compatible(struct 
vtd_iommu *iommu)
     if ( rdmsr_safe(MSR_IA32_VMX_EPT_VPID_CAP, ept_cap) != 0 ) 
         return 0;
 
-    return (ept_has_2mb(ept_cap) && opt_hap_2mb) == cap_sps_2mb(vtd_cap) &&
-           (ept_has_1gb(ept_cap) && opt_hap_1gb) == cap_sps_1gb(vtd_cap);
+    return (ept_has_2mb(ept_cap) && opt_hap_2mb) <= cap_sps_2mb(vtd_cap) &&
+           (ept_has_1gb(ept_cap) && opt_hap_1gb) <= cap_sps_1gb(vtd_cap);
 }
 
 /*
--
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