| From foo@baz Wed Feb 7 19:38:23 CST 2018 |
| From: Peter Zijlstra <peterz@infradead.org> |
| Date: Thu, 25 Jan 2018 10:58:13 +0100 |
| Subject: KVM: x86: Make indirect calls in emulator speculation safe |
| |
| From: Peter Zijlstra <peterz@infradead.org> |
| |
| (cherry picked from commit 1a29b5b7f347a1a9230c1e0af5b37e3e571588ab) |
| |
| Replace the indirect calls with CALL_NOSPEC. |
| |
| Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
| Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
| Reviewed-by: David Woodhouse <dwmw@amazon.co.uk> |
| Cc: Andrea Arcangeli <aarcange@redhat.com> |
| Cc: Andi Kleen <ak@linux.intel.com> |
| Cc: Ashok Raj <ashok.raj@intel.com> |
| Cc: Greg KH <gregkh@linuxfoundation.org> |
| Cc: Jun Nakajima <jun.nakajima@intel.com> |
| Cc: David Woodhouse <dwmw2@infradead.org> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: rga@amazon.de |
| Cc: Dave Hansen <dave.hansen@intel.com> |
| Cc: Asit Mallick <asit.k.mallick@intel.com> |
| Cc: Andy Lutomirski <luto@kernel.org> |
| Cc: Josh Poimboeuf <jpoimboe@redhat.com> |
| Cc: Jason Baron <jbaron@akamai.com> |
| Cc: Paolo Bonzini <pbonzini@redhat.com> |
| Cc: Dan Williams <dan.j.williams@intel.com> |
| Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com> |
| Cc: Tim Chen <tim.c.chen@linux.intel.com> |
| Link: https://lkml.kernel.org/r/20180125095843.595615683@infradead.org |
| [dwmw2: Use ASM_CALL_CONSTRAINT like upstream, now we have it] |
| Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| 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); |