This is a note to let you know that I've just added the patch titled KVM: x86: Make indirect calls in emulator speculation safe to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kvm-x86-make-indirect-calls-in-emulator-speculation-safe.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Wed Feb 7 19:38:23 CST 2018 From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Date: Thu, 25 Jan 2018 10:58:13 +0100 Subject: KVM: x86: Make indirect calls in emulator speculation safe From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> (cherry picked from commit 1a29b5b7f347a1a9230c1e0af5b37e3e571588ab) Replace the indirect calls with CALL_NOSPEC. Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Reviewed-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx> Cc: Ashok Raj <ashok.raj@xxxxxxxxx> Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Jun Nakajima <jun.nakajima@xxxxxxxxx> Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: rga@xxxxxxxxx Cc: Dave Hansen <dave.hansen@xxxxxxxxx> Cc: Asit Mallick <asit.k.mallick@xxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Cc: Jason Baron <jbaron@xxxxxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Arjan Van De Ven <arjan.van.de.ven@xxxxxxxxx> Cc: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20180125095843.595615683@xxxxxxxxxxxxx [dwmw2: Use ASM_CALL_CONSTRAINT like upstream, now we have it] Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kvm/emulate.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -25,6 +25,7 @@ #include <asm/kvm_emulate.h> #include <linux/stringify.h> #include <asm/debugreg.h> +#include <asm/nospec-branch.h> #include "x86.h" #include "tss.h" @@ -1012,8 +1013,8 @@ static __always_inline u8 test_cc(unsign void (*fop)(void) = (void *)em_setcc + 4 * (condition & 0xf); flags = (flags & EFLAGS_MASK) | X86_EFLAGS_IF; - asm("push %[flags]; popf; call *%[fastop]" - : "=a"(rc) : [fastop]"r"(fop), [flags]"r"(flags)); + asm("push %[flags]; popf; " CALL_NOSPEC + : "=a"(rc) : [thunk_target]"r"(fop), [flags]"r"(flags)); return rc; } @@ -5306,15 +5307,14 @@ static void fetch_possible_mmx_operand(s static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *)) { - register void *__sp asm(_ASM_SP); ulong flags = (ctxt->eflags & EFLAGS_MASK) | X86_EFLAGS_IF; if (!(ctxt->d & ByteOp)) fop += __ffs(ctxt->dst.bytes) * FASTOP_SIZE; - asm("push %[flags]; popf; call *%[fastop]; pushf; pop %[flags]\n" + asm("push %[flags]; popf; " CALL_NOSPEC " ; pushf; pop %[flags]\n" : "+a"(ctxt->dst.val), "+d"(ctxt->src.val), [flags]"+D"(flags), - [fastop]"+S"(fop), "+r"(__sp) + [thunk_target]"+S"(fop), ASM_CALL_CONSTRAINT : "c"(ctxt->src2.val)); ctxt->eflags = (ctxt->eflags & ~EFLAGS_MASK) | (flags & EFLAGS_MASK); Patches currently in stable-queue which might be from peterz@xxxxxxxxxxxxx are queue-4.9/kvm-x86-add-ibpb-support.patch queue-4.9/x86-cpufeatures-add-intel-feature-bits-for-speculation-control.patch queue-4.9/x86-cpufeatures-add-cpuid_7_edx-cpuid-leaf.patch queue-4.9/kvm-x86-make-indirect-calls-in-emulator-speculation-safe.patch queue-4.9/x86-cpufeature-blacklist-spec_ctrl-pred_cmd-on-early-spectre-v2-microcodes.patch queue-4.9/x86-asm-fix-inline-asm-call-constraints-for-gcc-4.4.patch queue-4.9/kvm-vmx-make-indirect-call-speculation-safe.patch queue-4.9/x86-cpufeatures-add-amd-feature-bits-for-speculation-control.patch queue-4.9/x86-msr-add-definitions-for-new-speculation-control-msrs.patch queue-4.9/x86-pti-make-unpoison-of-pgd-for-trusted-boot-work-for-real.patch queue-4.9/kaiser-fix-intel_bts-perf-crashes.patch queue-4.9/x86-retpoline-remove-the-esp-rsp-thunk.patch queue-4.9/x86-pti-do-not-enable-pti-on-cpus-which-are-not-vulnerable-to-meltdown.patch