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 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: KVM_x86_Make_indirect_calls_in_emulator_speculation_safe.patch and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

Subject: KVM: x86: Make indirect calls in emulator speculation safe From: Peter Zijlstra peterz@infradead.org Date: Thu Jan 25 10:58:13 2018 +0100

From: Peter Zijlstra peterz@infradead.org

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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/x86/kvm/emulate.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 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" @@ -1021,8 +1022,8 @@ 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; }

@@ -5335,9 +5336,9 @@ static int fastop(struct x86_emulate_ctx 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), ASM_CALL_CONSTRAINT + [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@infradead.org are

queue-4.15/x86pti_Do_not_enable_PTI_on_CPUs_which_are_not_vulnerable_to_Meltdown.patch queue-4.15/x86cpufeature_Blacklist_SPEC_CTRLPRED_CMD_on_early_Spectre_v2_microcodes.patch queue-4.15/x86cpufeatures_Add_Intel_feature_bits_for_Speculation_Control.patch queue-4.15/KVM_VMX_Make_indirect_call_speculation_safe.patch queue-4.15/x86msr_Add_definitions_for_new_speculation_control_MSRs.patch queue-4.15/x86alternative_Print_unadorned_pointers.patch queue-4.15/x86cpufeatures_Add_CPUID_7_EDX_CPUID_leaf.patch queue-4.15/x86bugs_Drop_one_mitigation_from_dmesg.patch queue-4.15/x86cpufeatures_Add_AMD_feature_bits_for_Speculation_Control.patch queue-4.15/x86speculation_Add_basic_IBPB_(Indirect_Branch_Prediction_Barrier)_support.patch queue-4.15/x86speculation_Simplify_indirect_branch_prediction_barrier().patch queue-4.15/x86nospec_Fix_header_guards_names.patch queue-4.15/KVM_x86_Make_indirect_calls_in_emulator_speculation_safe.patch queue-4.15/x86retpoline_Simplify_vmexit_fill_RSB().patch queue-4.15/x86cpufeatures_Clean_up_Spectre_v2_related_CPUID_flags.patch