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

KVM/nVMX: Set the CPU_BASED_USE_MSR_BITMAPS if we have a valid L02 MSR bitmap

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-set-the-cpu_based_use_msr_bitmaps-if-we-have-a-valid-l02-msr-bitmap.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 3712caeb14dcb33fb4d5114f14c0beef10aca101 Mon Sep 17 00:00:00 2001

From: KarimAllah Ahmed karahmed@amazon.de Date: Sat, 10 Feb 2018 23:39:26 +0000 Subject: KVM/nVMX: Set the CPU_BASED_USE_MSR_BITMAPS if we have a valid L02 MSR bitmap MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

From: KarimAllah Ahmed karahmed@amazon.de

commit 3712caeb14dcb33fb4d5114f14c0beef10aca101 upstream.

We either clear the CPU_BASED_USE_MSR_BITMAPS and end up intercepting all MSR accesses or create a valid L02 MSR bitmap and use that. This decision has to be made every time we evaluate whether we are going to generate the L02 MSR bitmap.

Before commit:

d28b387fb74d ("KVM/VMX: Allow direct access to MSR_IA32_SPEC_CTRL")

... this was probably OK since the decision was always identical.

This is no longer the case now since the MSR bitmap might actually change once we decide to not intercept SPEC_CTRL and PRED_CMD.

Signed-off-by: KarimAllah Ahmed karahmed@amazon.de Signed-off-by: David Woodhouse dwmw@amazon.co.uk Acked-by: Paolo Bonzini pbonzini@redhat.com Cc: Andy Lutomirski luto@kernel.org Cc: Arjan van de Ven arjan@linux.intel.com Cc: Borislav Petkov bp@alien8.de Cc: Dan Williams dan.j.williams@intel.com Cc: Dave Hansen dave.hansen@linux.intel.com Cc: David Woodhouse dwmw2@infradead.org Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Josh Poimboeuf jpoimboe@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Radim Krčmář rkrcmar@redhat.com Cc: Thomas Gleixner tglx@linutronix.de Cc: arjan.van.de.ven@intel.com Cc: dave.hansen@intel.com Cc: jmattson@google.com Cc: kvm@vger.kernel.org Cc: sironi@amazon.de Link: http://lkml.kernel.org/r/1518305967-31356-6-git-send-email-dwmw@amazon.co.uk Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/x86/kvm/vmx.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -10127,7 +10127,8 @@ static void nested_get_vmcs12_pages(stru if (cpu_has_vmx_msr_bitmap() && nested_cpu_has(vmcs12, CPU_BASED_USE_MSR_BITMAPS) && nested_vmx_merge_msr_bitmap(vcpu, vmcs12)) - ; + vmcs_set_bits(CPU_BASED_VM_EXEC_CONTROL, + CPU_BASED_USE_MSR_BITMAPS); else vmcs_clear_bits(CPU_BASED_VM_EXEC_CONTROL, CPU_BASED_USE_MSR_BITMAPS);

Patches currently in stable-queue which might be from karahmed@amazon.de are

queue-4.14/kvm-nvmx-set-the-cpu_based_use_msr_bitmaps-if-we-have-a-valid-l02-msr-bitmap.patch queue-4.14/x86-nvmx-properly-set-spec_ctrl-and-pred_cmd-before-merging-msrs.patch queue-4.14/x86-speculation-update-speculation-control-microcode-blacklist.patch queue-4.14/kvm-x86-reduce-retpoline-performance-impact-in-slot_handle_level_range-by-always-inlining-iterator-helper-methods.patch queue-4.14/revert-x86-speculation-simplify-indirect_branch_prediction_barrier.patch