Re: [PATCH v8 1/6] KVM: x86: Consolidate flags for __linearize()

[Binbin Wu]

On 5/10/2023 3:42 PM, Chao Gao wrote:
> On Wed, May 10, 2023 at 02:06:06PM +0800, Binbin Wu wrote:
> > Define a 32-bit parameter and consolidate the two bools into it.
> >
> > __linearize() has two bool parameters write and fetch. And new flag
> > will be needed to support new feature (e.g. LAM needs a flag to skip
> > address untag under some conditions).
> >
> > No functional change intended.
> >
> > In the follow-up patches, the new parameter will be extended for LAM.
> >
> > Signed-off-by: Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx>
> Reviewed-by: Chao Gao <chao.gao@xxxxxxxxx>
>
> one nit below
>
> > ---
> > arch/x86/kvm/emulate.c     | 19 +++++++++++++------
> > arch/x86/kvm/kvm_emulate.h |  4 ++++
> > 2 files changed, 17 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> > index 936a397a08cd..9508836e8a35 100644
> > --- a/arch/x86/kvm/emulate.c
> > +++ b/arch/x86/kvm/emulate.c
> > @@ -687,8 +687,8 @@ static unsigned insn_alignment(struct x86_emulate_ctxt *ctxt, unsigned size)
> > static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
> > 				       struct segmented_address addr,
> > 				       unsigned *max_size, unsigned size,
> > -				       bool write, bool fetch,
> > -				       enum x86emul_mode mode, ulong *linear)
> > +				       u32 flags, enum x86emul_mode mode,
> > +				       ulong *linear)
> > {
> > 	struct desc_struct desc;
> > 	bool usable;
> > @@ -696,6 +696,8 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
> > 	u32 lim;
> > 	u16 sel;
> > 	u8  va_bits;
> > +	bool fetch = !!(flags & X86EMUL_F_FETCH);
> > +	bool write = !!(flags & X86EMUL_F_WRITE);
> >
> > 	la = seg_base(ctxt, addr.seg) + addr.ea;
> > 	*max_size = 0;
> > @@ -757,7 +759,11 @@ static int linearize(struct x86_emulate_ctxt *ctxt,
> > 		     ulong *linear)
> > {
> > 	unsigned max_size;
> > -	return __linearize(ctxt, addr, &max_size, size, write, false,
> > +	u32 flags = 0;
> > +
> > +	if (write)
> > +		flags |= X86EMUL_F_WRITE;
> this can be more dense:
>
> 	u32 flags = write ? X86EMUL_F_WRITE : 0;
Thanks, will update it.