[xen stable-4.18] x86/HVM: hide SVM/VMX when their enabling is prohibited by firmware

[patchbot@xxxxxxx]

commit 3e383bb4137c6ca3058cd55cb867ecc2b7414499
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Mar 5 11:48:39 2024 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Mar 5 11:48:39 2024 +0100

    x86/HVM: hide SVM/VMX when their enabling is prohibited by firmware
    
    ... or we fail to enable the functionality on the BSP for other reasons.
    The only place where hardware announcing the feature is recorded is the
    raw CPU policy/featureset.
    
    Inspired by 
https://lore.kernel.org/all/20230921114940.957141-1-pbonzini@xxxxxxxxxx/.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    master commit: 0b5f149338e35a795bf609ce584640b0977f9e6c
    master date: 2024-01-09 14:06:34 +0100
---
 xen/arch/x86/hvm/svm/svm.c  |  1 +
 xen/arch/x86/hvm/vmx/vmcs.c | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 24c417ca71..ff991c82cf 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -2543,6 +2543,7 @@ const struct hvm_function_table * __init start_svm(void)
 
     if ( _svm_cpu_up(true) )
     {
+        setup_clear_cpu_cap(X86_FEATURE_SVM);
         printk("SVM: failed to initialise.\n");
         return NULL;
     }
diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 13719cc923..e382aa16c5 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -2165,6 +2165,23 @@ int __init vmx_vmcs_init(void)
 
     if ( !ret )
         register_keyhandler('v', vmcs_dump, "dump VT-x VMCSs", 1);
+    else
+    {
+        setup_clear_cpu_cap(X86_FEATURE_VMX);
+
+        /*
+         * _vmx_vcpu_up() may have made it past feature identification.
+         * Make sure all dependent features are off as well.
+         */
+        vmx_basic_msr              = 0;
+        vmx_pin_based_exec_control = 0;
+        vmx_cpu_based_exec_control = 0;
+        vmx_secondary_exec_control = 0;
+        vmx_vmexit_control         = 0;
+        vmx_vmentry_control        = 0;
+        vmx_ept_vpid_cap           = 0;
+        vmx_vmfunc                 = 0;
+    }
 
     return ret;
 }
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.18