[xen staging] VT-d: fix !HVM build

[patchbot@xxxxxxx]

commit c038304b46ffb3d3d314819d1331ca61e9ff668b
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri May 20 12:17:52 2022 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri May 20 12:17:52 2022 +0200

    VT-d: fix !HVM build
    
    EPT is of no interest when !HVM. While I'm observing gcc11 to fully
    eliminate the function, older gcc's DCE looks to not be as good.
    CONFIG_UBSAN apparently also limits how aggressively dead code is
    eliminated. Aid the compiler in eliminating the accesses of
    opt_hap_{2mb,1gb}, which otherwise cause undefined symbol errors when
    linking.
    
    While there adjust types.
    
    Fixes: c479415610f0 ("x86/P2M: p2m.c is HVM-only")
    Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/drivers/passthrough/vtd/iommu.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index f22caf269d..4ceb20632f 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -2206,14 +2206,17 @@ static int cf_check intel_iommu_lookup_page(
     return 0;
 }
 
-static int __init vtd_ept_page_compatible(struct vtd_iommu *iommu)
+static bool __init vtd_ept_page_compatible(const struct vtd_iommu *iommu)
 {
-    u64 ept_cap, vtd_cap = iommu->cap;
+    uint64_t ept_cap, vtd_cap = iommu->cap;
+
+    if ( !IS_ENABLED(CONFIG_HVM) )
+        return false;
 
     /* EPT is not initialised yet, so we must check the capability in
      * the MSR explicitly rather than use cpu_has_vmx_ept_*() */
     if ( rdmsr_safe(MSR_IA32_VMX_EPT_VPID_CAP, ept_cap) != 0 ) 
-        return 0;
+        return false;
 
     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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