From 161f6c16d82ed912f6b656c90572ca265a4f0f78 Mon Sep 17 00:00:00 2001 From: Andrew Cooper 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 Reviewed-by: Wei Liu Reviewed-by: Jan Beulich Release-acked-by: Juergen Gross (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 f419c36..f568265 100644 --- a/xen/include/asm-x86/cpufeatures.h +++ b/xen/include/asm-x86/cpufeatures.h @@ -28,8 +28,9 @@ XEN_CPUFEATURE(LFENCE_DISPATCH, (FSCAPINTS+0)*32+14) /* lfence set as Dispatch S 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 */ diff --git a/xen/include/asm-x86/spec_ctrl_asm.h b/xen/include/asm-x86/spec_ctrl_asm.h index b330e20..4d864eb 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. -- 2.1.4