Re: [Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-04-10 Thread Woods, Brian
On 2/1/19 8:49 AM, Andrew Cooper wrote: > c/s 9338a37d "x86/svm: implement debug events" added support for introspecting > ICEBP debug exceptions, but didn't account for the fact that > svm_get_insn_len() (previously __get_instruction_length) can fail and may > already raise #GP for the guest. > >

Re: [Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-02-05 Thread Jan Beulich
>>> On 04.02.19 at 20:44, wrote: > On 04/02/2019 09:16, Jan Beulich wrote: > On 01.02.19 at 18:09, wrote: >>> A subsequent #DB getting raised causes #GP to turn into #DF. >> The table on the #DF page clearly says >> otherwise, at least according to my reading. > > Hmm - so it does. Looks li

Re: [Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-02-05 Thread Jan Beulich
>>> On 04.02.19 at 20:44, wrote: > On 04/02/2019 09:16, Jan Beulich wrote: > On 01.02.19 at 18:09, wrote: >>> On 01/02/2019 16:55, Jan Beulich wrote: >>> On 01.02.19 at 17:25, wrote: > If it were just getting insn_len incorrectly as 0, then the guest would > livelock as we wouldn

Re: [Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-02-04 Thread Andrew Cooper
On 04/02/2019 09:16, Jan Beulich wrote: On 01.02.19 at 18:09, wrote: >> On 01/02/2019 16:55, Jan Beulich wrote: >> On 01.02.19 at 17:25, wrote: If it were just getting insn_len incorrectly as 0, then the guest would livelock as we wouldn't inject the #DB with trap semantics it

Re: [Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-02-04 Thread Jan Beulich
>>> On 01.02.19 at 18:09, wrote: > On 01/02/2019 16:55, Jan Beulich wrote: > On 01.02.19 at 17:25, wrote: >>> If it were just getting insn_len incorrectly as 0, then the guest would >>> livelock as we wouldn't inject the #DB with trap semantics it requires, >> I'm confused again: Why trap sem

Re: [Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-02-01 Thread Andrew Cooper
On 01/02/2019 16:55, Jan Beulich wrote: On 01.02.19 at 17:25, wrote: >> On 01/02/2019 15:58, Jan Beulich wrote: >> On 01.02.19 at 15:49, wrote: c/s 9338a37d "x86/svm: implement debug events" added support for introspecting ICEBP debug exceptions, but didn't account for th

Re: [Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-02-01 Thread Jan Beulich
>>> On 01.02.19 at 17:25, wrote: > On 01/02/2019 15:58, Jan Beulich wrote: > On 01.02.19 at 15:49, wrote: >>> c/s 9338a37d "x86/svm: implement debug events" added support for >>> introspecting >>> ICEBP debug exceptions, but didn't account for the fact that >>> svm_get_insn_len() (previously

Re: [Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-02-01 Thread Andrew Cooper
On 01/02/2019 15:58, Jan Beulich wrote: On 01.02.19 at 15:49, wrote: >> c/s 9338a37d "x86/svm: implement debug events" added support for >> introspecting >> ICEBP debug exceptions, but didn't account for the fact that >> svm_get_insn_len() (previously __get_instruction_length) can fail and m

Re: [Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-02-01 Thread Jan Beulich
>>> On 01.02.19 at 15:49, wrote: > c/s 9338a37d "x86/svm: implement debug events" added support for introspecting > ICEBP debug exceptions, but didn't account for the fact that > svm_get_insn_len() (previously __get_instruction_length) can fail and may > already raise #GP for the guest. > > If sv

Re: [Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-02-01 Thread Tamas K Lengyel
On Fri, Feb 1, 2019 at 7:49 AM Andrew Cooper wrote: > > c/s 9338a37d "x86/svm: implement debug events" added support for introspecting > ICEBP debug exceptions, but didn't account for the fact that > svm_get_insn_len() (previously __get_instruction_length) can fail and may > already raise #GP for

Re: [Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-02-01 Thread Razvan Cojocaru
On 2/1/19 4:49 PM, Andrew Cooper wrote: c/s 9338a37d "x86/svm: implement debug events" added support for introspecting ICEBP debug exceptions, but didn't account for the fact that svm_get_insn_len() (previously __get_instruction_length) can fail and may already raise #GP for the guest. If svm_ge

Re: [Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-02-01 Thread Juergen Gross
On 01/02/2019 15:49, Andrew Cooper wrote: > c/s 9338a37d "x86/svm: implement debug events" added support for introspecting > ICEBP debug exceptions, but didn't account for the fact that > svm_get_insn_len() (previously __get_instruction_length) can fail and may > already raise #GP for the guest. >

[Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-02-01 Thread Andrew Cooper
c/s 9338a37d "x86/svm: implement debug events" added support for introspecting ICEBP debug exceptions, but didn't account for the fact that svm_get_insn_len() (previously __get_instruction_length) can fail and may already raise #GP for the guest. If svm_get_insn_len() fails, return back to guest c

Re: [Xen-devel] [PATCH for-4.12] x86/svm: Fix handling of ICEBP intercepts

2019-02-01 Thread Andrew Cooper
On 01/02/2019 14:52, Tamas K Lengyel wrote: > On Fri, Feb 1, 2019 at 7:49 AM Andrew Cooper > wrote: >> c/s 9338a37d "x86/svm: implement debug events" added support for >> introspecting >> ICEBP debug exceptions, but didn't account for the fact that >> svm_get_insn_len() (previously __get_instruc