[PATCH v6 0/5] KVM: Expose speculation control feature to guests

[KarimAllah Ahmed <karahmed@amazon.de>]

Add direct access to speculation control MSRs for KVM guests. This allows the
guest to protect itself against Spectre V2 using IBRS+IBPB instead of a
retpoline+IBPB based approach.

It also exposes the ARCH_CAPABILITIES MSR which is used by Intel processors to
indicate RDCL_NO and IBRS_ALL.

Keep in mind that the SVM part of the patch is unchanged this time. Mostly to
get feedback/confirmation about the nested handling for VMX first, once this is
done I will update SVM as well.

v6:
- Do not penalize (save/restore IBRS) all L2 guests when anyone of them starts
  using the SPEC_CTRL.

v5:
- svm: add PRED_CMD and SPEC_CTRL to direct_access_msrs list.
- vmx: check also for X86_FEATURE_SPEC_CTRL for msr reads and writes.
- vmx: Use MSR_TYPE_W instead of MSR_TYPE_R for the nested IBPB MSR
- rewrite commit message for IBPB patch [2/5] (Ashok)

v4:
- Add IBRS passthrough for SVM (5/5).
- Handle nested guests properly.
- expose F(IBRS) in kvm_cpuid_8000_0008_ebx_x86_features

Ashok Raj (1):
  KVM: x86: Add IBPB support

KarimAllah Ahmed (4):
  KVM: x86: Update the reverse_cpuid list to include CPUID_7_EDX
  KVM: VMX: Emulate MSR_IA32_ARCH_CAPABILITIES
  KVM: VMX: Allow direct access to MSR_IA32_SPEC_CTRL
  KVM: SVM: Allow direct access to MSR_IA32_SPEC_CTRL

 arch/x86/kvm/cpuid.c |  22 ++++--
 arch/x86/kvm/cpuid.h |   1 +
 arch/x86/kvm/svm.c   |  87 +++++++++++++++++++++++
 arch/x86/kvm/vmx.c   | 196 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 arch/x86/kvm/x86.c   |   1 +
 5 files changed, 299 insertions(+), 8 deletions(-)

Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Asit Mallick <asit.k.mallick@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.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: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: x86@kernel.org

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2.7.4