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>
Release-acked-by: Juergen Gross <jgross@suse.com>

diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c
index c7ec9a34d591ddbe842251bb26cdf64c2c6f8186..0978e1c1acaf9452c7f73afbe1cec992d5580162 100644 (file)
--- a/xen/arch/x86/spec_ctrl.c
+++ b/xen/arch/x86/spec_ctrl.c
@@ -128,7 +128,8 @@ static void __init print_details(enum ind_thunk thunk, uint64_t caps)
            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"       : "",
@@ -367,7 +368,8 @@ void __init init_speculation_mitigations(void)
          * 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;

diff --git a/xen/include/asm-x86/cpufeatures.h b/xen/include/asm-x86/cpufeatures.h
index 32b7f0457ecd60a46a2d48d0d740514cd9c9c76e..b90aa2d046140dfff5503e1cad8e22f881893a8f 100644 (file)
--- a/xen/include/asm-x86/cpufeatures.h
+++ b/xen/include/asm-x86/cpufeatures.h
@@ -26,8 +26,9 @@ XEN_CPUFEATURE(LFENCE_DISPATCH, (FSCAPINTS+0)*32+12) /* lfence set as Dispatch S
 XEN_CPUFEATURE(IND_THUNK_LFENCE,(FSCAPINTS+0)*32+13) /* Use IND_THUNK_LFENCE */
 XEN_CPUFEATURE(IND_THUNK_JMP,   (FSCAPINTS+0)*32+14) /* Use IND_THUNK_JMP */
 XEN_CPUFEATURE(XEN_IBPB,        (FSCAPINTS+0)*32+15) /* IBRSB || IBPB */
-XEN_CPUFEATURE(SC_MSR,          (FSCAPINTS+0)*32+16) /* MSR_SPEC_CTRL used by Xen */
+XEN_CPUFEATURE(SC_MSR_PV,       (FSCAPINTS+0)*32+16) /* MSR_SPEC_CTRL used by Xen for PV */
+XEN_CPUFEATURE(SC_MSR_HVM,      (FSCAPINTS+0)*32+17) /* MSR_SPEC_CTRL used by Xen for HVM */
 XEN_CPUFEATURE(SC_RSB_PV,       (FSCAPINTS+0)*32+18) /* RSB overwrite needed for PV */
 XEN_CPUFEATURE(SC_RSB_HVM,      (FSCAPINTS+0)*32+19) /* RSB overwrite needed for HVM */
 XEN_CPUFEATURE(NO_XPTI,         (FSCAPINTS+0)*32+20) /* XPTI mitigation not in use */
-XEN_CPUFEATURE(SC_MSR_IDLE,     (FSCAPINTS+0)*32+21) /* SC_MSR && default_xen_spec_ctrl */
+XEN_CPUFEATURE(SC_MSR_IDLE,     (FSCAPINTS+0)*32+21) /* (SC_MSR_PV || SC_MSR_HVM) && default_xen_spec_ctrl */

diff --git a/xen/include/asm-x86/spec_ctrl_asm.h b/xen/include/asm-x86/spec_ctrl_asm.h
index bf36b5a8868b6548342ba07c83285d1b1e14f73e..edace2a04e8ab41c61d12a33baff9f4702008beb 100644 (file)
--- a/xen/include/asm-x86/spec_ctrl_asm.h
+++ b/xen/include/asm-x86/spec_ctrl_asm.h
@@ -223,34 +223,34 @@
 #define SPEC_CTRL_ENTRY_FROM_HVM                                        \
     ALTERNATIVE "", DO_OVERWRITE_RSB, X86_FEATURE_SC_RSB_HVM;           \
     ALTERNATIVE "", DO_SPEC_CTRL_ENTRY_FROM_HVM,                        \
-        X86_FEATURE_SC_MSR
+        X86_FEATURE_SC_MSR_HVM
 
 /* Use after an entry from PV context (syscall/sysenter/int80/int82/etc). */
 #define SPEC_CTRL_ENTRY_FROM_PV                                         \
     ALTERNATIVE "", DO_OVERWRITE_RSB, X86_FEATURE_SC_RSB_PV;            \
     ALTERNATIVE "", __stringify(DO_SPEC_CTRL_ENTRY maybexen=0),         \
-        X86_FEATURE_SC_MSR
+        X86_FEATURE_SC_MSR_PV
 
 /* Use in interrupt/exception context.  May interrupt Xen or PV context. */
 #define SPEC_CTRL_ENTRY_FROM_INTR                                       \
     ALTERNATIVE "", DO_OVERWRITE_RSB, X86_FEATURE_SC_RSB_PV;            \
     ALTERNATIVE "", __stringify(DO_SPEC_CTRL_ENTRY maybexen=1),         \
-        X86_FEATURE_SC_MSR
+        X86_FEATURE_SC_MSR_PV
 
 /* Use when exiting to Xen context. */
 #define SPEC_CTRL_EXIT_TO_XEN                                           \
     ALTERNATIVE "",                                                     \
-        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 "",                                                     \
-        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 "",                                                     \
-        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.