From 2acc4cba7eb2559bafdd4d8238466ad81322a35a Mon Sep 17 00:00:00 2001
From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Tue, 17 Apr 2018 14:15:04 +0100
Subject: [PATCH] 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>
(cherry picked from commit fa9eb09d446a1279f5e861e6b84fa8675dabf148)
---
xen/arch/x86/spec_ctrl.c | 6 ++++--
xen/include/asm-x86/cpufeatures.h | 5 +++--
xen/include/asm-x86/spec_ctrl_asm.h | 12 ++++++------
3 files changed, 13 insertions(+), 10 deletions(-)
diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c
index 55ef79f..a940308 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.
*/
- 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 32b7f04..b90aa2d 100644
--- 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 3d156ed..c659f3f 100644
--- a/xen/include/asm-x86/spec_ctrl_asm.h
+++ b/xen/include/asm-x86/spec_ctrl_asm.h
@@ -224,36 +224,36 @@
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.
--
2.1.4
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