Re: [PATCH v5 17/19] KVM: VMX: Use VMX_FEATURE_* flags to define VMCS control bits

Sean Christopherson
2020-01-13T18:37:12Z

On Mon, Jan 13, 2020 at 07:32:28PM +0100, Borislav Petkov wrote:
> On Fri, Dec 20, 2019 at 08:45:11PM -0800, Sean Christopherson wrote:
> > Define the VMCS execution control flags (consumed by KVM) using their
> > associated VMX_FEATURE_* to provide a strong hint that new VMX features
> > are expected to be added to VMX_FEATURE and considered for reporting via
> > /proc/cpuinfo.
> >
> > No functional change intended.
> >
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > ---
> > arch/x86/include/asm/vmx.h | 105 +++++++++++++++++++------------------
> > 1 file changed, 55 insertions(+), 50 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> > index 1835767aa335..9fbba31be825 100644
> > --- a/arch/x86/include/asm/vmx.h
> > +++ b/arch/x86/include/asm/vmx.h
> > @@ -15,67 +15,70 @@
> > #include <linux/bitops.h>
> > #include <linux/types.h>
> > #include <uapi/asm/vmx.h>
> > +#include <asm/vmxfeatures.h>
> > +
> > +#define VMCS_CONTROL_BIT(x) BIT(VMX_FEATURE_##x & 0x1f)
> >
> > /*
> > * Definitions of Primary Processor-Based VM-Execution Controls.
> > */
> > -#define CPU_BASED_VIRTUAL_INTR_PENDING 0x00000004
> > -#define CPU_BASED_USE_TSC_OFFSETING 0x00000008
> > -#define CPU_BASED_HLT_EXITING 0x00000080
> > -#define CPU_BASED_INVLPG_EXITING 0x00000200
> > -#define CPU_BASED_MWAIT_EXITING 0x00000400
> > -#define CPU_BASED_RDPMC_EXITING 0x00000800
> > -#define CPU_BASED_RDTSC_EXITING 0x00001000
> > -#define CPU_BASED_CR3_LOAD_EXITING 0x00008000
> > -#define CPU_BASED_CR3_STORE_EXITING 0x00010000
> > -#define CPU_BASED_CR8_LOAD_EXITING 0x00080000
> > -#define CPU_BASED_CR8_STORE_EXITING 0x00100000
> > -#define CPU_BASED_TPR_SHADOW 0x00200000
> > -#define CPU_BASED_VIRTUAL_NMI_PENDING 0x00400000
> > -#define CPU_BASED_MOV_DR_EXITING 0x00800000
> > -#define CPU_BASED_UNCOND_IO_EXITING 0x01000000
> > -#define CPU_BASED_USE_IO_BITMAPS 0x02000000
> > -#define CPU_BASED_MONITOR_TRAP_FLAG 0x08000000
> > -#define CPU_BASED_USE_MSR_BITMAPS 0x10000000
> > -#define CPU_BASED_MONITOR_EXITING 0x20000000
> > -#define CPU_BASED_PAUSE_EXITING 0x40000000
> > -#define CPU_BASED_ACTIVATE_SECONDARY_CONTROLS 0x80000000
> > +#define CPU_BASED_VIRTUAL_INTR_PENDING VMCS_CONTROL_BIT(VIRTUAL_INTR_PENDING)
> > +#define CPU_BASED_USE_TSC_OFFSETING VMCS_CONTROL_BIT(TSC_OFFSETTING)
>
> checkpatch correctly complains here:
>
> WARNING: 'OFFSETING' may be misspelled - perhaps 'OFFSETTING'?
> #80: FILE: arch/x86/include/asm/vmx.h:26:
> +#define CPU_BASED_USE_TSC_OFFSETING VMCS_CONTROL_BIT(TSC_OFFSETTING)
>
> and VMX_FEATURE_TSC_OFFSETTING is correct.
>
> Should I fix it up to CPU_BASED_USE_TSC_OFFSETTING while applying?

No, the CPU_BASED_* defines are used by existing KVM code, i.e. you'd
also have to touch a bunch of KVM code.

$ git grep CPU_BASED_USE_TSC_OFFSETING
arch/x86/include/asm/vmx.h:#define CPU_BASED_USE_TSC_OFFSETING 0x00000008
arch/x86/kvm/vmx/nested.c: if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)
arch/x86/kvm/vmx/nested.c: if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)
arch/x86/kvm/vmx/nested.c: if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)
arch/x86/kvm/vmx/nested.c: CPU_BASED_VIRTUAL_NMI_PENDING | CPU_BASED_USE_TSC_OFFSETING |
arch/x86/kvm/vmx/vmx.c: (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING))
arch/x86/kvm/vmx/vmx.c: (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING))
arch/x86/kvm/vmx/vmx.c: CPU_BASED_USE_TSC_OFFSETING |
tools/testing/selftests/kvm/include/x86_64/vmx.h:#define CPU_BASED_USE_TSC_OFFSETING 0x00000008
tools/testing/selftests/kvm/x86_64/vmx_tsc_adjust_test.c: control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_USE_TSC_OFFSETING;