[xen stable-4.20] x86/PVH: expose OEMx ACPI tables to Dom0

[patchbot@xxxxxxx]

commit a1f8f1e6818848e1112e7835cdc4696131f8f0dd
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Mar 27 14:58:59 2025 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Mar 27 14:58:59 2025 +0100

    x86/PVH: expose OEMx ACPI tables to Dom0
    
    What they contain we don't know, but we can't sensibly hide them. On my
    Skylake system OEM1 (with a description of "INTEL  CPU EIST") is what
    contains all the _PCT, _PPC, and _PSS methods, i.e. about everything
    needed for cpufreq. (_PSD interestingly are in an SSDT there.)
    
    Further OEM2 there has a description of "INTEL  CPU  HWP", while OEM4
    has "INTEL  CPU  CST". Pretty clearly all three need exposing for
    cpufreq and cpuidle to work.
    
    Fixes: 8b1a5268daf0 ("pvh/dom0: whitelist PVH Dom0 ACPI tables")
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    master commit: 6378909b41c40187a79df1d38ca4791b34393d67
    master date: 2025-03-26 12:32:03 +0100
---
 xen/arch/x86/hvm/dom0_build.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/xen/arch/x86/hvm/dom0_build.c b/xen/arch/x86/hvm/dom0_build.c
index 6591949984..60c56e126d 100644
--- a/xen/arch/x86/hvm/dom0_build.c
+++ b/xen/arch/x86/hvm/dom0_build.c
@@ -1011,12 +1011,20 @@ static bool __init pvh_acpi_table_allowed(const char 
*sig,
             return true;
         else
         {
+    skip:
             printk("Skipping table %.4s in non-ACPI non-reserved region\n",
                    sig);
             return false;
         }
     }
 
+    if ( !strncmp(sig, "OEM", 3) )
+    {
+        if ( acpi_memory_banned(address, size) )
+            goto skip;
+        return true;
+    }
+
     return false;
 }
 
--
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