| Message ID | 1483617604-4990-2-git-send-email-andrew.cooper3@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
>>> On 05.01.17 at 13:00, <andrew.cooper3@citrix.com> wrote: > --- a/xen/arch/x86/traps.c > +++ b/xen/arch/x86/traps.c > @@ -2169,6 +2169,19 @@ static int priv_op_read_segment(enum x86_segment seg, > struct segment_register *reg, > struct x86_emulate_ctxt *ctxt) > { > + /* Check if this is an attempt to access to I/O bitmap. */ > + if ( seg == x86_seg_tr ) > + { > + switch ( ctxt->opcode ) > + { > + case 0x6c ... 0x6f: /* ins / outs */ > + case 0xe4 ... 0xe7: /* in / out (immediate port) */ > + case 0xec ... 0xef: /* in / out (port in %dx) */ > + /* Defer the check to priv_op_{read,write}_io(). */ > + return X86EMUL_DONE; > + } > + } Well, I think I did like the old way a little better, but if you prefer this switch(), then fine. When putting together my variant of the change for testing I did notice the comment to have a wrong "to" (should be "the"), so with that adjusted Reviewed-by: Jan Beulich <jbeulich@suse.com> Jan
On 05/01/17 12:15, Jan Beulich wrote: >>>> On 05.01.17 at 13:00, <andrew.cooper3@citrix.com> wrote: >> --- a/xen/arch/x86/traps.c >> +++ b/xen/arch/x86/traps.c >> @@ -2169,6 +2169,19 @@ static int priv_op_read_segment(enum x86_segment seg, >> struct segment_register *reg, >> struct x86_emulate_ctxt *ctxt) >> { >> + /* Check if this is an attempt to access to I/O bitmap. */ >> + if ( seg == x86_seg_tr ) >> + { >> + switch ( ctxt->opcode ) >> + { >> + case 0x6c ... 0x6f: /* ins / outs */ >> + case 0xe4 ... 0xe7: /* in / out (immediate port) */ >> + case 0xec ... 0xef: /* in / out (port in %dx) */ >> + /* Defer the check to priv_op_{read,write}_io(). */ >> + return X86EMUL_DONE; >> + } >> + } > Well, I think I did like the old way a little better, but if you prefer this > switch(), then fine. When putting together my variant of the change for > testing I did notice the comment to have a wrong "to" (should be "the"), So it is. Will fix. > so with that adjusted > Reviewed-by: Jan Beulich <jbeulich@suse.com> Thanks. ~Andrew
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c index a33109d..ea559e9 100644 --- a/xen/arch/x86/traps.c +++ b/xen/arch/x86/traps.c @@ -2169,6 +2169,19 @@ static int priv_op_read_segment(enum x86_segment seg, struct segment_register *reg, struct x86_emulate_ctxt *ctxt) { + /* Check if this is an attempt to access to I/O bitmap. */ + if ( seg == x86_seg_tr ) + { + switch ( ctxt->opcode ) + { + case 0x6c ... 0x6f: /* ins / outs */ + case 0xe4 ... 0xe7: /* in / out (immediate port) */ + case 0xec ... 0xef: /* in / out (port in %dx) */ + /* Defer the check to priv_op_{read,write}_io(). */ + return X86EMUL_DONE; + } + } + if ( ctxt->addr_size < 64 ) { unsigned long limit; @@ -2182,11 +2195,6 @@ static int priv_op_read_segment(enum x86_segment seg, case x86_seg_fs: sel = read_sreg(fs); break; case x86_seg_gs: sel = read_sreg(gs); break; case x86_seg_ss: sel = ctxt->regs->ss; break; - case x86_seg_tr: - /* Check if this is an attempt to access to I/O bitmap. */ - if ( (ctxt->opcode & ~0xb) == 0xe4 || (ctxt->opcode & ~3) == 0x6c ) - return X86EMUL_DONE; - /* fall through */ default: return X86EMUL_UNHANDLEABLE; }
The I/O bitmap doesn't change function depending on mode. 64bit userspace such as an X server still needs to enter guest_io_okay() to find that the PV kernel did set up an appropriate virtual I/O bitmap to permit access. While moving the check, alter its representation to be easier to read. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> --- CC: Jan Beulich <JBeulich@suse.com> --- xen/arch/x86/traps.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-)