Patch "KVM: x86: emulate #UD while in guest mode" has been added to the 4.14-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    KVM: x86: emulate #UD while in guest mode

to the 4.14-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-emulate-ud-while-in-guest-mode.patch
and it can be found in the queue-4.14 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.


>From foo@baz Thu Feb  1 13:45:42 CET 2018
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Thu, 11 Jan 2018 16:55:24 +0100
Subject: KVM: x86: emulate #UD while in guest mode

From: Paolo Bonzini <pbonzini@redhat.com>


[ Upstream commit bd89525a823ce6edddcedbe9aed79faa1b9cf544 ]

This reverts commits ae1f57670703656cc9f293722c3b8b6782f8ab3f
and ac9b305caa0df6f5b75d294e4b86c1027648991e.

If the hardware doesn't support MOVBE, but L0 sets CPUID.01H:ECX.MOVBE
in L1's emulated CPUID information, then L1 is likely to pass that
CPUID bit through to L2. L2 will expect MOVBE to work, but if L1
doesn't intercept #UD, then any MOVBE instruction executed in L2 will
raise #UD, and the exception will be delivered in L2.

Commit ac9b305caa0df6f5b75d294e4b86c1027648991e is a better and more
complete version of ae1f57670703 ("KVM: nVMX: Do not emulate #UD while
in guest mode"); however, neither considers the above case.

Suggested-by: Jim Mattson <jmattson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/kvm/svm.c |    9 +--------
 arch/x86/kvm/vmx.c |    5 +----
 2 files changed, 2 insertions(+), 12 deletions(-)

--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -362,7 +362,6 @@ static void recalc_intercepts(struct vcp
 {
 	struct vmcb_control_area *c, *h;
 	struct nested_state *g;
-	u32 h_intercept_exceptions;
 
 	mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
 
@@ -373,14 +372,9 @@ static void recalc_intercepts(struct vcp
 	h = &svm->nested.hsave->control;
 	g = &svm->nested;
 
-	/* No need to intercept #UD if L1 doesn't intercept it */
-	h_intercept_exceptions =
-		h->intercept_exceptions & ~(1U << UD_VECTOR);
-
 	c->intercept_cr = h->intercept_cr | g->intercept_cr;
 	c->intercept_dr = h->intercept_dr | g->intercept_dr;
-	c->intercept_exceptions =
-		h_intercept_exceptions | g->intercept_exceptions;
+	c->intercept_exceptions = h->intercept_exceptions | g->intercept_exceptions;
 	c->intercept = h->intercept | g->intercept;
 }
 
@@ -2195,7 +2189,6 @@ static int ud_interception(struct vcpu_s
 {
 	int er;
 
-	WARN_ON_ONCE(is_guest_mode(&svm->vcpu));
 	er = emulate_instruction(&svm->vcpu, EMULTYPE_TRAP_UD);
 	if (er == EMULATE_USER_EXIT)
 		return 0;
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1891,7 +1891,7 @@ static void update_exception_bitmap(stru
 {
 	u32 eb;
 
-	eb = (1u << PF_VECTOR) | (1u << MC_VECTOR) |
+	eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) |
 	     (1u << DB_VECTOR) | (1u << AC_VECTOR);
 	if ((vcpu->guest_debug &
 	     (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) ==
@@ -1909,8 +1909,6 @@ static void update_exception_bitmap(stru
 	 */
 	if (is_guest_mode(vcpu))
 		eb |= get_vmcs12(vcpu)->exception_bitmap;
-	else
-		eb |= 1u << UD_VECTOR;
 
 	vmcs_write32(EXCEPTION_BITMAP, eb);
 }
@@ -5921,7 +5919,6 @@ static int handle_exception(struct kvm_v
 		return 1;  /* already handled by vmx_vcpu_run() */
 
 	if (is_invalid_opcode(intr_info)) {
-		WARN_ON_ONCE(is_guest_mode(vcpu));
 		er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
 		if (er == EMULATE_USER_EXIT)
 			return 0;


Patches currently in stable-queue which might be from pbonzini@redhat.com are

queue-4.14/kvm-nvmx-fix-mmu-context-after-vmlaunch-vmresume-failure.patch
queue-4.14/kvm-vmx-fix-rflags-cache-during-vcpu-reset.patch
queue-4.14/kvm-x86-emulate-ud-while-in-guest-mode.patch
queue-4.14/kvm-x86-fix-operand-address-size-during-instruction-decoding.patch
queue-4.14/kvm-nvmx-nsvm-don-t-intercept-ud-when-running-l2.patch
queue-4.14/kvm-let-kvm_set_signal_mask-work-as-advertised.patch
queue-4.14/kvm-x86-fix-softlockup-when-get-the-current-kvmclock.patch