> -----Original Message----- > From: xen-devel-boun...@lists.xen.org [mailto:xen-devel- > boun...@lists.xen.org] On Behalf Of Jan Beulich > Sent: 08 July 2015 16:53 > To: Andrew Cooper; Paul Durrant > Cc: xen-de...@lists.xenproject.org; Keir (Xen.org) > Subject: Re: [Xen-devel] [PATCH v6 02/16] x86/hvm: remove multiple open > coded 'chunking' loops > > >>> On 03.07.15 at 18:25, <paul.durr...@citrix.com> wrote: > > +static int hvmemul_linear_mmio_access( > > + unsigned long gla, unsigned int size, uint8_t dir, uint8_t *buffer, > > + uint32_t pfec, struct hvm_emulate_ctxt *hvmemul_ctxt, bool_t > known_gpfn) > > +{ > > + struct hvm_vcpu_io *vio = ¤t->arch.hvm_vcpu.hvm_io; > > + unsigned long offset = gla & ~PAGE_MASK; > > + unsigned int chunk; > > + paddr_t gpa; > > + unsigned long one_rep = 1; > > + int rc; > > + > > + chunk = min_t(unsigned int, size, PAGE_SIZE - offset); > > + > > + if ( known_gpfn ) > > + gpa = pfn_to_paddr(vio->mmio_gpfn) | offset; > > + else > > + { > > + rc = hvmemul_linear_to_phys(gla, &gpa, chunk, &one_rep, pfec, > > + hvmemul_ctxt); > > + if ( rc != X86EMUL_OKAY ) > > + return rc; > > + } > > + > > + for ( ;; ) > > + { > > + rc = hvmemul_phys_mmio_access(gpa, chunk, dir, buffer); > > + if ( rc != X86EMUL_OKAY ) > > + break; > > + > > + gla += chunk; > > + buffer += chunk; > > + size -= chunk; > > + > > + if ( size == 0 ) > > + break; > > + > > + ASSERT((gla & ~PAGE_MASK) == 0); > > Does this really matter for the code below? > > > + chunk = min_t(unsigned int, size, PAGE_SIZE); > > Iirc Andrew had asked for this, but I still don't see why: "size" is the > width of an instruction operand, and hence won't even come close > to PAGE_SIZE. >
I'll let Andrew answer that one. I've already ping-ponged once on this. I guess it makes it safer if someone were to try to use this function for another purpose in future? Paul > > + rc = hvmemul_linear_to_phys(gla, &gpa, chunk, &one_rep, pfec, > > + hvmemul_ctxt); > > The fact that &one_rep is being passed here also makes clear that > we can't be dealing with an <operand-width> * <reps> situation. > And if we were, "size" couldn't validly be "unsigned int". > > Jan > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
