Patch "KVM: x86: Make indirect calls in emulator speculation safe" has been added to the 4.15-stable tree

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;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-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Subject: KVM: x86: Make indirect calls in emulator speculation safe
From: Peter Zijlstra [email protected]
Date: Thu Jan 25 10:58:13 2018 +0100

From: Peter Zijlstra [email protected]

commit 1a29b5b7f347a1a9230c1e0af5b37e3e571588ab

Replace the indirect calls with CALL_NOSPEC.

---
 arch/x86/kvm/emulate.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

@@ -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 [email protected] 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