[Xen-changelog] [xen stable-4.7] x86/spec_ctrl: Split X86_FEATURE_SC_MSR into PV and HVM variants

[patchbot@xxxxxxx]

commit 0b5b62a6942cd92c2a5ec87561ad9e8a83a8ce89
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Tue May 29 10:33:09 2018 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue May 29 10:33:09 2018 +0200

    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@xxxxxxxxxx>
    Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    master commit: fa9eb09d446a1279f5e861e6b84fa8675dabf148
    master date: 2018-05-16 12:19:10 +0100
---
 xen/arch/x86/cpu/common.c           |  7 +++++--
 xen/arch/x86/spec_ctrl.c            |  6 ++++--
 xen/include/asm-x86/cpufeature.h    |  5 +++--
 xen/include/asm-x86/spec_ctrl_asm.h | 12 ++++++------
 4 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index e1c479a72d..147c83d942 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -417,9 +417,12 @@ void identify_cpu(struct cpuinfo_x86 *c)
                if (test_bit(X86_FEATURE_IND_THUNK_JMP,
                             boot_cpu_data.x86_capability))
                        __set_bit(X86_FEATURE_IND_THUNK_JMP, c->x86_capability);
-               if (test_bit(X86_FEATURE_SC_MSR,
+               if (test_bit(X86_FEATURE_SC_MSR_PV,
                             boot_cpu_data.x86_capability))
-                       __set_bit(X86_FEATURE_SC_MSR, c->x86_capability);
+                       __set_bit(X86_FEATURE_SC_MSR_PV, c->x86_capability);
+               if (test_bit(X86_FEATURE_SC_MSR_HVM,
+                            boot_cpu_data.x86_capability))
+                       __set_bit(X86_FEATURE_SC_MSR_HVM, c->x86_capability);
                if (test_bit(X86_FEATURE_SC_RSB_PV,
                             boot_cpu_data.x86_capability))
                        __set_bit(X86_FEATURE_SC_RSB_PV, c->x86_capability);
diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c
index 410f248757..b4bc5d009d 100644
--- a/xen/arch/x86/spec_ctrl.c
+++ b/xen/arch/x86/spec_ctrl.c
@@ -112,7 +112,8 @@ 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"       : "",
@@ -286,7 +287,8 @@ void __init init_speculation_mitigations(void)
          * need the IBRS entry/exit logic to virtualise IBRS support for
          * guests.
          */
-        __set_bit(X86_FEATURE_SC_MSR, boot_cpu_data.x86_capability);
+        __set_bit(X86_FEATURE_SC_MSR_PV, boot_cpu_data.x86_capability);
+        __set_bit(X86_FEATURE_SC_MSR_HVM, boot_cpu_data.x86_capability);
 
         if ( ibrs )
             default_xen_spec_ctrl |= SPEC_CTRL_IBRS;
diff --git a/xen/include/asm-x86/cpufeature.h b/xen/include/asm-x86/cpufeature.h
index 2466f5b7f7..d6b995157e 100644
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -30,11 +30,12 @@
 #define X86_FEATURE_IND_THUNK_LFENCE   ((FSCAPINTS+0)*32+ 11) /* Use 
IND_THUNK_LFENCE */
 #define X86_FEATURE_IND_THUNK_JMP      ((FSCAPINTS+0)*32+ 12) /* Use 
IND_THUNK_JMP */
 #define X86_FEATURE_XEN_IBPB           ((FSCAPINTS+0)*32+ 13) /* IBRSB || IBPB 
*/
-#define X86_FEATURE_SC_MSR             ((FSCAPINTS+0)*32+ 14) /* MSR_SPEC_CTRL 
used by Xen */
+#define X86_FEATURE_SC_MSR_PV          ((FSCAPINTS+0)*32+ 14) /* MSR_SPEC_CTRL 
used by Xen for PV */
+#define X86_FEATURE_SC_MSR_HVM         ((FSCAPINTS+0)*32+ 15) /* MSR_SPEC_CTRL 
used by Xen for HVM */
 #define X86_FEATURE_SC_RSB_PV          ((FSCAPINTS+0)*32+ 16) /* RSB overwrite 
needed for PV */
 #define X86_FEATURE_SC_RSB_HVM         ((FSCAPINTS+0)*32+ 17) /* RSB overwrite 
needed for HVM */
 #define X86_FEATURE_NO_XPTI            ((FSCAPINTS+0)*32+ 18) /* XPTI 
mitigation not in use */
-#define X86_FEATURE_SC_MSR_IDLE                ((FSCAPINTS+0)*32+ 19) /* 
SC_MSR && default_xen_spec_ctrl */
+#define X86_FEATURE_SC_MSR_IDLE                ((FSCAPINTS+0)*32+ 19) /* 
(SC_MSR_PV || SC_MSR_HVM) && default_xen_spec_ctrl */
 
 #define cpufeat_word(idx)      ((idx) / 32)
 #define cpufeat_bit(idx)       ((idx) % 32)
diff --git a/xen/include/asm-x86/spec_ctrl_asm.h 
b/xen/include/asm-x86/spec_ctrl_asm.h
index b330e20e0e..4d864eb4ec 100644
--- 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.
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.7

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/xen-changelog