On Mon, May 29, 2023 at 06:48:03PM +0200, Mickaël Salaün wrote: > > On 08/05/2023 23:11, Wei Liu wrote: > > On Fri, May 05, 2023 at 05:20:42PM +0200, Mickaël Salaün wrote: > > > This enables guests to lock their CR0 and CR4 registers with a subset of > > > X86_CR0_WP, X86_CR4_SMEP, X86_CR4_SMAP, X86_CR4_UMIP, X86_CR4_FSGSBASE > > > and X86_CR4_CET flags. > > > > > > The new KVM_HC_LOCK_CR_UPDATE hypercall takes two arguments. The first > > > is to identify the control register, and the second is a bit mask to > > > pin (i.e. mark as read-only). > > > > > > These register flags should already be pinned by Linux guests, but once > > > compromised, this self-protection mechanism could be disabled, which is > > > not the case with this dedicated hypercall. > > > > > > Cc: Borislav Petkov <b...@alien8.de> > > > Cc: Dave Hansen <dave.han...@linux.intel.com> > > > Cc: H. Peter Anvin <h...@zytor.com> > > > Cc: Ingo Molnar <mi...@redhat.com> > > > Cc: Kees Cook <keesc...@chromium.org> > > > Cc: Madhavan T. Venkataraman <madve...@linux.microsoft.com> > > > Cc: Paolo Bonzini <pbonz...@redhat.com> > > > Cc: Sean Christopherson <sea...@google.com> > > > Cc: Thomas Gleixner <t...@linutronix.de> > > > Cc: Vitaly Kuznetsov <vkuzn...@redhat.com> > > > Cc: Wanpeng Li <wanpen...@tencent.com> > > > Signed-off-by: Mickaël Salaün <m...@digikod.net> > > > Link: https://lore.kernel.org/r/20230505152046.6575-6-...@digikod.net > > [...] > > > hw_cr4 = (cr4_read_shadow() & X86_CR4_MCE) | (cr4 & > > > ~X86_CR4_MCE); > > > if (is_unrestricted_guest(vcpu)) > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > > index ffab64d08de3..a529455359ac 100644 > > > --- a/arch/x86/kvm/x86.c > > > +++ b/arch/x86/kvm/x86.c > > > @@ -7927,11 +7927,77 @@ static unsigned long emulator_get_cr(struct > > > x86_emulate_ctxt *ctxt, int cr) > > > return value; > > > } > > > +#ifdef CONFIG_HEKI > > > + > > > +extern unsigned long cr4_pinned_mask; > > > + > > > > Can this be moved to a header file? > > Yep, but I'm not sure which one. Any preference Kees?
Uh, er, I was never expecting that mask to be non-static. ;) To that end, how about putting it in arch/x86/kvm/x86.h ? -- Kees Cook
