File 5b02c786-x86-msr-virtualise-SPEC_CTRL-SSBD.patch of Package xen.8005

# Commit cd53023df952cf0084be9ee3d15a90f8837049c2
# Date 2018-05-21 14:20:06 +0100
# Author Andrew Cooper <andrew.cooper3@citrix.com>
# Committer Andrew Cooper <andrew.cooper3@citrix.com>
x86/msr: Virtualise MSR_SPEC_CTRL.SSBD for guests to use

Almost all infrastructure is already in place.  Update the reserved bits
calculation in guest_wrmsr().

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1360,7 +1360,8 @@ long arch_do_domctl(
                      * ignored) when STIBP isn't enumerated in hardware.
                      */
 
-                    if ( msr.value & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP) )
+                    if ( msr.value & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP |
+                                       (boot_cpu_has(X86_FEATURE_SSBD) ? SPEC_CTRL_SSBD : 0)) )
                         break;
                     v->arch.spec_ctrl = msr.value;
                     continue;
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3548,7 +3548,9 @@ int hvm_msr_write_intercept(unsigned int
          * when STIBP isn't enumerated in hardware.
          */
 
-        if ( msr_content & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP) )
+        if ( msr_content & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP |
+                             (edx & cpufeat_mask(X86_FEATURE_SSBD)
+                              ? SPEC_CTRL_SSBD : 0)) )
             goto gp_fault; /* Rsvd bit set? */
 
         v->arch.spec_ctrl = msr_content;
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -2603,7 +2603,9 @@ static int emulate_privileged_op(struct
              * when STIBP isn't enumerated in hardware.
              */
 
-            if ( msr_content & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP) )
+            if ( msr_content & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP |
+                                 (edx & cpufeat_mask(X86_FEATURE_SSBD)
+                                  ? SPEC_CTRL_SSBD : 0)) )
                 goto fail; /* Rsvd bit set? */
 
             v->arch.spec_ctrl = eax;