• Konrad Rzeszutek Wilk's avatar
    x86/bugs: Add AMD's SPEC_CTRL MSR usage · 6ac2f49e
    Konrad Rzeszutek Wilk authored
    The AMD document outlining the SSBD handling
    124441_AMD64_SpeculativeStoreBypassDisable_Whitepaper_final.pdf
    mentions that if CPUID 8000_0008.EBX[24] is set we should be using
    the SPEC_CTRL MSR (0x48) over the VIRT SPEC_CTRL MSR (0xC001_011f)
    for speculative store bypass disable.
    
    This in effect means we should clear the X86_FEATURE_VIRT_SSBD
    flag so that we would prefer the SPEC_CTRL MSR.
    
    See the document titled:
       124441_AMD64_SpeculativeStoreBypassDisable_Whitepaper_final.pdf
    
    A copy of this document is available at
       https://bugzilla.kernel.org/show_bug.cgi?id=199889Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Cc: Tom Lendacky <thomas.lendacky@amd.com>
    Cc: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
    Cc: kvm@vger.kernel.org
    Cc: KarimAllah Ahmed <karahmed@amazon.de>
    Cc: andrew.cooper3@citrix.com
    Cc: Joerg Roedel <joro@8bytes.org>
    Cc: Radim Krčmář <rkrcmar@redhat.com>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: Borislav Petkov <bp@suse.de>
    Cc: David Woodhouse <dwmw@amazon.co.uk>
    Cc: Kees Cook <keescook@chromium.org>
    Link: https://lkml.kernel.org/r/20180601145921.9500-3-konrad.wilk@oracle.com
    6ac2f49e
svm.c 182 KB