[tip:x86/pti] KVM/nVMX: Set the CPU_BASED_USE_MSR_BITMAPS if we have a valid L02 MSR bitmap

tip-bot for KarimAllah Ahmed
2018-02-11T12:10:48Z

Commit-ID: ff37dc0cd96c266c7700386b7ba48abc32a91b1f
Gitweb: https://git.kernel.org/tip/ff37dc0cd96c266c7700386b7ba48abc32a91b1f
Author: KarimAllah Ahmed <karahmed@amazon.de>
AuthorDate: Sat, 10 Feb 2018 23:39:26 +0000
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Sun, 11 Feb 2018 11:24:16 +0100

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

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>
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: Paolo Bonzini <pbonzini@redhat.com>
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>
---
arch/x86/kvm/vmx.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 599179b..91e3539 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10130,7 +10130,8 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu,
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);