On Tue, Dec 13, 2022 at 2:11 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > Use a dedicated entry for invoking the NMI handler from KVM VMX's VM-Exit > path for 32-bit even though using a dedicated entry for 32-bit isn't > strictly necessary. Exposing a single symbol will allow KVM to reference > the entry point in assembly code without having to resort to more #ifdefs > (or #defines). identry.h is intended to be included from asm files only > once, and so simply including idtentry.h in KVM assembly isn't an option. > > Bypassing the ESP fixup and CR3 switching in the standard NMI entry code > is safe as KVM always handles NMIs that occur in the guest on a kernel > stack, with a kernel CR3. > > Cc: Andy Lutomirski <luto@xxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> > --- > arch/x86/include/asm/idtentry.h | 16 ++++++---------- > arch/x86/kernel/nmi.c | 8 ++++---- > arch/x86/kvm/vmx/vmx.c | 4 ++-- > 3 files changed, 12 insertions(+), 16 deletions(-) > > diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h > index 72184b0b2219..b241af4ce9b4 100644 > --- a/arch/x86/include/asm/idtentry.h > +++ b/arch/x86/include/asm/idtentry.h > @@ -582,18 +582,14 @@ DECLARE_IDTENTRY_RAW(X86_TRAP_MC, xenpv_exc_machine_check); > > /* NMI */ > > -#if defined(CONFIG_X86_64) && IS_ENABLED(CONFIG_KVM_INTEL) > +#if IS_ENABLED(CONFIG_KVM_INTEL) > /* > - * Special NOIST entry point for VMX which invokes this on the kernel > - * stack. asm_exc_nmi() requires an IST to work correctly vs. the NMI > - * 'executing' marker. > - * > - * On 32bit this just uses the regular NMI entry point because 32-bit does > - * not have ISTs. > + * Special entry point for VMX which invokes this on the kernel stack, even for > + * 64-bit, i.e. without using an IST. asm_exc_nmi() requires an IST to work > + * correctly vs. the NMI 'executing' marker. Used for 32-bit kernels as well > + * to avoid more ifdeffery. > */ > -DECLARE_IDTENTRY(X86_TRAP_NMI, exc_nmi_noist); > -#else > -#define asm_exc_nmi_noist asm_exc_nmi > +DECLARE_IDTENTRY(X86_TRAP_NMI, exc_nmi_kvm_vmx); Reviewed-by: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
