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%3Ba=su...

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