[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 3/4] x86/hvm: Optimise segment accesses in hvmemul_write_segment()
> -----Original Message----- > From: Andrew Cooper [mailto:andrew.cooper3@xxxxxxxxxx] > Sent: 08 September 2016 15:12 > To: Xen-devel <xen-devel@xxxxxxxxxxxxx> > Cc: Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>; Jan Beulich > <JBeulich@xxxxxxxx>; Paul Durrant <Paul.Durrant@xxxxxxxxxx> > Subject: [PATCH 3/4] x86/hvm: Optimise segment accesses in > hvmemul_write_segment() > > There is no need to read the segment information from VMCS/VMCB and > cache it, just to clobber the cached content immediately afterwards. > > Write straight into the cache and set the accessed/dirty bits. > Yes, the way the code is now does look somewhat silly. > Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> > --- > CC: Jan Beulich <JBeulich@xxxxxxxx> > CC: Paul Durrant <paul.durrant@xxxxxxxxxx> Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx> > --- > xen/arch/x86/hvm/emulate.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c > index 0eb7a4d..e3bfda5 100644 > --- a/xen/arch/x86/hvm/emulate.c > +++ b/xen/arch/x86/hvm/emulate.c > @@ -1447,12 +1447,12 @@ static int hvmemul_write_segment( { > struct hvm_emulate_ctxt *hvmemul_ctxt = > container_of(ctxt, struct hvm_emulate_ctxt, ctxt); > - struct segment_register *sreg = hvmemul_get_seg_reg(seg, > hvmemul_ctxt); > > - if ( IS_ERR(sreg) ) > - return -PTR_ERR(sreg); > + if ( seg < 0 || seg >= ARRAY_SIZE(hvmemul_ctxt->seg_reg) ) > + return X86EMUL_UNHANDLEABLE; > > - memcpy(sreg, reg, sizeof(struct segment_register)); > + hvmemul_ctxt->seg_reg[seg] = *reg; > + __set_bit(seg, &hvmemul_ctxt->seg_reg_accessed); > __set_bit(seg, &hvmemul_ctxt->seg_reg_dirty); > > return X86EMUL_OKAY; > -- > 2.1.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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