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

KVM: nVMX/nSVM: Don't intercept #UD when running L2

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-nvmx-nsvm-don-t-intercept-ud-when-running-l2.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: Liran Alon liran.alon@oracle.com Date: Mon, 6 Nov 2017 16:15:10 +0200 Subject: KVM: nVMX/nSVM: Don't intercept #UD when running L2

From: Liran Alon liran.alon@oracle.com

[ Upstream commit ac9b305caa0df6f5b75d294e4b86c1027648991e ]

When running L2, #UD should be intercepted by L1 or just forwarded directly to L2. It should not reach L0 x86 emulator. Therefore, set intercept for #UD only based on L1 exception-bitmap.

Also add WARN_ON_ONCE() on L0 #UD intercept handlers to make sure it is never reached while running L2.

This improves commit ae1f57670703 ("KVM: nVMX: Do not emulate #UD while in guest mode") by removing an unnecessary exit from L2 to L0 on #UD when L1 doesn't intercept it.

In addition, SVM L0 #UD intercept handler doesn't handle correctly the case it is raised from L2. In this case, it should forward the #UD to guest instead of x86 emulator. As done in VMX #UD intercept handler. This commit fixes this issue as-well.

Signed-off-by: Liran Alon liran.alon@oracle.com Reviewed-by: Nikita Leshenko nikita.leshchenko@oracle.com Reviewed-by: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Signed-off-by: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Reviewed-by: Paolo Bonzini pbonzini@redhat.com Reviewed-by: Wanpeng Li wanpeng.li@hotmail.com Signed-off-by: Radim Krčmář rkrcmar@redhat.com Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/svm.c | 9 ++++++++- arch/x86/kvm/vmx.c | 9 ++++----- 2 files changed, 12 insertions(+), 6 deletions(-)

--- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -362,6 +362,7 @@ 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);

@@ -372,9 +373,14 @@ 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; }

@@ -2189,6 +2195,7 @@ 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 << UD_VECTOR) | (1u << MC_VECTOR) | + eb = (1u << PF_VECTOR) | (1u << MC_VECTOR) | (1u << DB_VECTOR) | (1u << AC_VECTOR); if ((vcpu->guest_debug & (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) == @@ -1909,6 +1909,8 @@ 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); } @@ -5919,10 +5921,7 @@ static int handle_exception(struct kvm_v return 1; /* already handled by vmx_vcpu_run() */

if (is_invalid_opcode(intr_info)) { - if (is_guest_mode(vcpu)) { - kvm_queue_exception(vcpu, UD_VECTOR); - return 1; - } + 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 liran.alon@oracle.com are

queue-4.14/kvm-nvmx-fix-vmx_check_nested_events-return-value-in-case-an-event-was-reinjected-to-l2.patch queue-4.14/kvm-x86-don-t-re-execute-instruction-when-not-passing-cr2-value.patch queue-4.14/kvm-x86-ioapic-preserve-read-only-values-in-the-redirection-table.patch queue-4.14/kvm-x86-ioapic-fix-level-triggered-eoi-and-ioapic-reconfigure-race.patch queue-4.14/kvm-x86-emulator-return-to-user-mode-on-l1-cpl-0-emulation-failure.patch queue-4.14/kvm-nvmx-nsvm-don-t-intercept-ud-when-running-l2.patch queue-4.14/kvm-x86-ioapic-clear-remote-irr-when-entry-is-switched-to-edge-triggered.patch