# Commit fa9eb09d446a1279f5e861e6b84fa8675dabf148
# Date 2018-05-16 12:19:10 +0100
# Author Andrew Cooper <andrew.cooper3@citrix.com>
# Committer Andrew Cooper <andrew.cooper3@citrix.com>
x86/spec_ctrl: Split X86_FEATURE_SC_MSR into PV and HVM variants

In order to separately control whether MSR_SPEC_CTRL is virtualised for PV and
HVM guests, split the feature used to control runtime alternatives into two.
Xen will use MSR_SPEC_CTRL itself if either of these features are active.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/spec_ctrl.c
+++ b/xen/arch/x86/spec_ctrl.c
@@ -112,7 +112,8 @@ static void __init print_details(enum in
            thunk == THUNK_RETPOLINE ? "RETPOLINE" :
            thunk == THUNK_LFENCE    ? "LFENCE" :
            thunk == THUNK_JMP       ? "JMP" : "?",
-           boot_cpu_has(X86_FEATURE_SC_MSR) ?
+           (boot_cpu_has(X86_FEATURE_SC_MSR_PV) ||
+            boot_cpu_has(X86_FEATURE_SC_MSR_HVM)) ?
            default_xen_spec_ctrl & SPEC_CTRL_IBRS    ? " IBRS+" :
                                                        " IBRS-"      : "",
            opt_ibpb                                  ? " IBPB"       : "",
@@ -286,7 +287,8 @@ void __init init_speculation_mitigations
          * need the IBRS entry/exit logic to virtualise IBRS support for
          * guests.
          */
-        setup_force_cpu_cap(X86_FEATURE_SC_MSR);
+        setup_force_cpu_cap(X86_FEATURE_SC_MSR_PV);
+        setup_force_cpu_cap(X86_FEATURE_SC_MSR_HVM);
 
         if ( ibrs )
             default_xen_spec_ctrl |= SPEC_CTRL_IBRS;
--- a/xen/include/asm-x86/cpufeatures.h
+++ b/xen/include/asm-x86/cpufeatures.h
@@ -28,8 +28,9 @@ XEN_CPUFEATURE(LFENCE_DISPATCH, (FSCAPIN
 XEN_CPUFEATURE(IND_THUNK_LFENCE,(FSCAPINTS+0)*32+15) /* Use IND_THUNK_LFENCE */
 XEN_CPUFEATURE(IND_THUNK_JMP,   (FSCAPINTS+0)*32+16) /* Use IND_THUNK_JMP */
 XEN_CPUFEATURE(XEN_IBPB,        (FSCAPINTS+0)*32+17) /* IBRSB || IBPB */
-XEN_CPUFEATURE(SC_MSR,          (FSCAPINTS+0)*32+18) /* MSR_SPEC_CTRL used by Xen */
+XEN_CPUFEATURE(SC_MSR_PV,       (FSCAPINTS+0)*32+18) /* MSR_SPEC_CTRL used by Xen for PV */
+XEN_CPUFEATURE(SC_MSR_HVM,      (FSCAPINTS+0)*32+19) /* MSR_SPEC_CTRL used by Xen for HVM */
 XEN_CPUFEATURE(SC_RSB_PV,       (FSCAPINTS+0)*32+20) /* RSB overwrite needed for PV */
 XEN_CPUFEATURE(SC_RSB_HVM,      (FSCAPINTS+0)*32+21) /* RSB overwrite needed for HVM */
 XEN_CPUFEATURE(NO_XPTI,         (FSCAPINTS+0)*32+22) /* XPTI mitigation not in use */
-XEN_CPUFEATURE(SC_MSR_IDLE,     (FSCAPINTS+0)*32+23) /* SC_MSR && default_xen_spec_ctrl */
+XEN_CPUFEATURE(SC_MSR_IDLE,     (FSCAPINTS+0)*32+23) /* (SC_MSR_PV || SC_MSR_HVM) && default_xen_spec_ctrl */
--- a/xen/include/asm-x86/spec_ctrl_asm.h
+++ b/xen/include/asm-x86/spec_ctrl_asm.h
@@ -223,36 +223,36 @@
     ALTERNATIVE __stringify(ASM_NOP40),                                 \
         DO_OVERWRITE_RSB, X86_FEATURE_SC_RSB_HVM;                       \
     ALTERNATIVE __stringify(ASM_NOP36),                                 \
-        DO_SPEC_CTRL_ENTRY_FROM_HVM, X86_FEATURE_SC_MSR
+        DO_SPEC_CTRL_ENTRY_FROM_HVM, X86_FEATURE_SC_MSR_HVM
 
 /* Use after an entry from PV context (syscall/sysenter/int80/int82/etc). */
 #define SPEC_CTRL_ENTRY_FROM_PV                                         \
     ALTERNATIVE __stringify(ASM_NOP40),                                 \
         DO_OVERWRITE_RSB, X86_FEATURE_SC_RSB_PV;                        \
     ALTERNATIVE __stringify(ASM_NOP25),                                 \
-        __stringify(DO_SPEC_CTRL_ENTRY maybexen=0), X86_FEATURE_SC_MSR
+        __stringify(DO_SPEC_CTRL_ENTRY maybexen=0), X86_FEATURE_SC_MSR_PV
 
 /* Use in interrupt/exception context.  May interrupt Xen or PV context. */
 #define SPEC_CTRL_ENTRY_FROM_INTR                                       \
     ALTERNATIVE __stringify(ASM_NOP40),                                 \
         DO_OVERWRITE_RSB, X86_FEATURE_SC_RSB_PV;                        \
     ALTERNATIVE __stringify(ASM_NOP33),                                 \
-        __stringify(DO_SPEC_CTRL_ENTRY maybexen=1), X86_FEATURE_SC_MSR
+        __stringify(DO_SPEC_CTRL_ENTRY maybexen=1), X86_FEATURE_SC_MSR_PV
 
 /* Use when exiting to Xen context. */
 #define SPEC_CTRL_EXIT_TO_XEN                                           \
     ALTERNATIVE __stringify(ASM_NOP17),                                 \
-        DO_SPEC_CTRL_EXIT_TO_XEN, X86_FEATURE_SC_MSR
+        DO_SPEC_CTRL_EXIT_TO_XEN, X86_FEATURE_SC_MSR_PV
 
 /* Use when exiting to PV guest context. */
 #define SPEC_CTRL_EXIT_TO_PV                                            \
     ALTERNATIVE __stringify(ASM_NOP24),                                 \
-        DO_SPEC_CTRL_EXIT_TO_GUEST, X86_FEATURE_SC_MSR
+        DO_SPEC_CTRL_EXIT_TO_GUEST, X86_FEATURE_SC_MSR_PV
 
 /* Use when exiting to HVM guest context. */
 #define SPEC_CTRL_EXIT_TO_HVM                                           \
     ALTERNATIVE __stringify(ASM_NOP24),                                 \
-        DO_SPEC_CTRL_EXIT_TO_GUEST, X86_FEATURE_SC_MSR
+        DO_SPEC_CTRL_EXIT_TO_GUEST, X86_FEATURE_SC_MSR_HVM
 
 /*
  * Use in IST interrupt/exception context.  May interrupt Xen or PV context.
