We already flush all domain-related caches after reconfigurations,
irrespective of the address ranges changed and how they were changed
(made valid or invalid). So the feature check during unit setup is
actually superfluous - remove it.

Signed-off-by: Jan Kiszka <[email protected]>
---
 hypervisor/arch/x86/vtd.c      | 4 ----
 tools/jailhouse-hardware-check | 1 -
 2 files changed, 5 deletions(-)

diff --git a/hypervisor/arch/x86/vtd.c b/hypervisor/arch/x86/vtd.c
index f3cba65..aaed326 100644
--- a/hypervisor/arch/x86/vtd.c
+++ b/hypervisor/arch/x86/vtd.c
@@ -48,7 +48,6 @@ struct vtd_entry {
 # define VTD_VER_MIN                   0x10
 #define VTD_CAP_REG                    0x08
 # define VTD_CAP_NUM_DID_MASK          BIT_MASK(2, 0)
-# define VTD_CAP_CM                    (1UL << 7)
 # define VTD_CAP_SAGAW39               (1UL << 9)
 # define VTD_CAP_SAGAW48               (1UL << 10)
 # define VTD_CAP_SLLPS2M               (1UL << 34)
@@ -653,9 +652,6 @@ int iommu_init(void)
                        return trace_error(-EIO);
                dmar_pt_levels = pt_levels;
 
-               if (caps & VTD_CAP_CM)
-                       return trace_error(-EIO);
-
                ecaps = mmio_read64(reg_base + VTD_ECAP_REG);
                if (!(ecaps & VTD_ECAP_QI) || !(ecaps & VTD_ECAP_IR) ||
                    (using_x2apic && !(ecaps & VTD_ECAP_EIM)))
diff --git a/tools/jailhouse-hardware-check b/tools/jailhouse-hardware-check
index fa69580..cf3762c 100755
--- a/tools/jailhouse-hardware-check
+++ b/tools/jailhouse-hardware-check
@@ -225,7 +225,6 @@ if cpu_vendor == 'GenuineIntel':
             break
         mmio = MMIO(iommu[n].base, iommu[n].size)
         cap = mmio.read64(0x08)
-        check_feature('  Caching mode = 0', (cap & (1 << 7)) == 0)
         check_feature('  39-bit AGAW', cap & (1 << 9), cap & (1 << 10))
         check_feature('  48-bit AGAW', cap & (1 << 10), cap & (1 << 9))
         check_feature('  2M pages', cap & (1 << 34), True)
-- 
2.1.4

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