> -----Original Message-----
> From: Jan Beulich [mailto:jbeul...@suse.com]
> Sent: 07 December 2017 14:18
> To: xen-devel <xen-devel@lists.xenproject.org>
> Cc: Andrew Cooper <andrew.coop...@citrix.com>; Paul Durrant
> <paul.durr...@citrix.com>; George Dunlap <george.dun...@citrix.com>
> Subject: [PATCH v3 23/25] x86/HVM: make use of new read-modify-write
> emulator hook
>
> ..., at least as far as currently possible, i.e. when a mapping can be
> obtained.
>
> Signed-off-by: Jan Beulich <jbeul...@suse.com>
Reviewed-by: Paul Durrant <paul.durr...@citrix.com>
> ---
> v3: New.
>
> --- a/xen/arch/x86/hvm/emulate.c
> +++ b/xen/arch/x86/hvm/emulate.c
> @@ -1187,6 +1187,61 @@ static int hvmemul_write(
> return X86EMUL_OKAY;
> }
>
> +static int hvmemul_rmw(
> + enum x86_segment seg,
> + unsigned long offset,
> + unsigned int bytes,
> + uint32_t *eflags,
> + struct x86_emulate_state *state,
> + struct x86_emulate_ctxt *ctxt)
> +{
> + struct hvm_emulate_ctxt *hvmemul_ctxt =
> + container_of(ctxt, struct hvm_emulate_ctxt, ctxt);
> + unsigned long addr, reps = 1;
> + uint32_t pfec = PFEC_page_present | PFEC_write_access;
> + struct hvm_vcpu_io *vio = ¤t->arch.hvm_vcpu.hvm_io;
> + int rc;
> + void *mapping;
> +
> + rc = hvmemul_virtual_to_linear(
> + seg, offset, bytes, &reps, hvm_access_write, hvmemul_ctxt, &addr);
> + if ( rc != X86EMUL_OKAY || !bytes )
> + return rc;
> +
> + if ( is_x86_system_segment(seg) )
> + pfec |= PFEC_implicit;
> + else if ( hvmemul_ctxt->seg_reg[x86_seg_ss].dpl == 3 )
> + pfec |= PFEC_user_mode;
> +
> + mapping = hvmemul_map_linear_addr(addr, bytes, pfec,
> hvmemul_ctxt);
> + if ( IS_ERR(mapping) )
> + return ~PTR_ERR(mapping);
> +
> + if ( mapping )
> + {
> + rc = x86_emul_rmw(mapping, bytes, eflags, state, ctxt);
> + hvmemul_unmap_linear_addr(mapping, addr, bytes, hvmemul_ctxt);
> + }
> + else
> + {
> + unsigned long data = 0;
> + bool_t known_gpfn = vio->mmio_access.write_access &&
> + vio->mmio_gla == (addr & PAGE_MASK);
> +
> + if ( bytes > sizeof(data) )
> + return X86EMUL_UNHANDLEABLE;
> + rc = hvmemul_linear_mmio_read(addr, bytes, &data, pfec,
> hvmemul_ctxt,
> + known_gpfn);
> + if ( rc == X86EMUL_OKAY )
> + rc = x86_emul_rmw(&data, bytes, eflags, state, ctxt);
> + if ( rc == X86EMUL_OKAY )
> + rc = hvmemul_linear_mmio_write(addr, bytes, &data, pfec,
> + hvmemul_ctxt, known_gpfn);
> + }
> +
> + return rc;
> +}
> +
> static int hvmemul_write_discard(
> enum x86_segment seg,
> unsigned long offset,
> @@ -2157,6 +2212,7 @@ static const struct x86_emulate_ops hvm_
> .read = hvmemul_read,
> .insn_fetch = hvmemul_insn_fetch,
> .write = hvmemul_write,
> + .rmw = hvmemul_rmw,
> .cmpxchg = hvmemul_cmpxchg,
> .validate = hvmemul_validate,
> .rep_ins = hvmemul_rep_ins,
>
>
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