The AMD Zen4 core supports a new feature called Automatic IBRS (Indirect Branch Restricted Speculation). Enable Automatic IBRS by default if the CPU feature is present. It typically provides greater performance over the incumbent generic retpolines mitigation. Patch 1 adds support for AutoIBRS and other feature bits in the CPUID_8000_0021_EAX leaf. Patch 2 adds support for AMD Automatic IBRS Co-developed-by: Babu Moger <Babu.Moger@xxxxxxx> Co-developed-by: Borislav Petkov <bp@xxxxxxxxx> Signed-off-by: Kim Phillips <kim.phillips@xxxxxxx> Cc: Borislav Petkov <bp@xxxxxxx> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Joao Martins <joao.m.martins@xxxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Sean Christopherson <seanjc@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: David Woodhouse <dwmw@xxxxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Juergen Gross <jgross@xxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Tony Luck <tony.luck@xxxxxxxxx> Cc: Tom Lendacky <thomas.lendacky@xxxxxxx> Cc: kvm@xxxxxxxxxxxxxxx Cc: linux-doc@xxxxxxxxxxxxxxx Cc: x86@xxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Kim Phillips (2): x86/cpu, kvm: Use CPU capabilities for CPUID[0x80000021].EAX x86/cpu, kvm: Support AMD Automatic IBRS .../admin-guide/kernel-parameters.txt | 9 +++-- arch/x86/include/asm/cpufeatures.h | 5 +-- arch/x86/include/asm/msr-index.h | 2 ++ arch/x86/kernel/cpu/bugs.c | 23 +++++++----- arch/x86/kernel/cpu/common.c | 8 +++++ arch/x86/kernel/cpu/scattered.c | 4 +++ arch/x86/kvm/cpuid.c | 35 +++++++++++-------- arch/x86/kvm/reverse_cpuid.h | 24 +++++++++---- arch/x86/kvm/svm/svm.c | 3 ++ arch/x86/kvm/x86.c | 3 ++ 10 files changed, 82 insertions(+), 34 deletions(-) -- 2.34.1
