| Message ID | 20190502214203.17279-1-tamas@tklengyel.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] x86/vm_event: add gdtr_base to the vm_event structure | expand |
On 5/3/19 12:42 AM, Tamas K Lengyel wrote: > Receiving this register is useful for introspecting 32-bit Windows when the > event being trapped happened while in ring3. > > Signed-off-by: Tamas K Lengyel <tamas@tklengyel.com> > Cc: Razvan Cojocaru <rcojocaru@bitdefender.com> > Cc: Tamas K Lengyel <tamas@tklengyel.com> > Cc: Jan Beulich <jbeulich@suse.com> > Cc: Andrew Cooper <andrew.cooper3@citrix.com> > Cc: Wei Liu <wei.liu2@citrix.com> > Cc: Roger Pau Monne <roger.pau@citrix.com> > --- > v2: add gdtr limit Acked-by: Razvan Cojocaru <rcojocaru@bitdefender.com> Thanks, Razvan
On Thu, May 2, 2019 at 3:42 PM Tamas K Lengyel <tamas@tklengyel.com> wrote: > > Receiving this register is useful for introspecting 32-bit Windows when the > event being trapped happened while in ring3. > > Signed-off-by: Tamas K Lengyel <tamas@tklengyel.com> > Cc: Razvan Cojocaru <rcojocaru@bitdefender.com> > Cc: Tamas K Lengyel <tamas@tklengyel.com> > Cc: Jan Beulich <jbeulich@suse.com> > Cc: Andrew Cooper <andrew.cooper3@citrix.com> > Cc: Wei Liu <wei.liu2@citrix.com> > Cc: Roger Pau Monne <roger.pau@citrix.com> > --- > v2: add gdtr limit > --- > xen/arch/x86/vm_event.c | 6 ++++++ > xen/include/public/vm_event.h | 6 ++++-- > 2 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/xen/arch/x86/vm_event.c b/xen/arch/x86/vm_event.c > index 51c3493b1d..52c2a71fa0 100644 > --- a/xen/arch/x86/vm_event.c > +++ b/xen/arch/x86/vm_event.c > @@ -179,6 +179,11 @@ static void vm_event_pack_segment_register(enum x86_segment segment, > reg->es_sel = seg.sel; > break; > > + case x86_seg_gdtr: > + reg->gdtr_base = seg.base; > + reg->gdtr_limit = seg.limit; > + break; > + > default: > ASSERT_UNREACHABLE(); > } > @@ -238,6 +243,7 @@ void vm_event_fill_regs(vm_event_request_t *req) > vm_event_pack_segment_register(x86_seg_ss, &req->data.regs.x86); > vm_event_pack_segment_register(x86_seg_ds, &req->data.regs.x86); > vm_event_pack_segment_register(x86_seg_es, &req->data.regs.x86); > + vm_event_pack_segment_register(x86_seg_gdtr, &req->data.regs.x86); > > req->data.regs.x86.shadow_gs = ctxt.shadow_gs; > req->data.regs.x86.dr6 = ctxt.dr6; > diff --git a/xen/include/public/vm_event.h b/xen/include/public/vm_event.h > index b2bafc0d77..959083d8c4 100644 > --- a/xen/include/public/vm_event.h > +++ b/xen/include/public/vm_event.h > @@ -29,7 +29,7 @@ > > #include "xen.h" > > -#define VM_EVENT_INTERFACE_VERSION 0x00000004 > +#define VM_EVENT_INTERFACE_VERSION 0x00000005 > > #if defined(__XEN__) || defined(__XEN_TOOLS__) > > @@ -198,6 +198,7 @@ struct vm_event_regs_x86 { > uint64_t msr_efer; > uint64_t msr_star; > uint64_t msr_lstar; > + uint64_t gdtr_base; > uint32_t cs_base; > uint32_t ss_base; > uint32_t ds_base; > @@ -211,13 +212,14 @@ struct vm_event_regs_x86 { > struct vm_event_x86_selector_reg fs; > struct vm_event_x86_selector_reg gs; > uint64_t shadow_gs; > + uint16_t gdtr_limit; Whoops, just noticed that limit actually needs 20-bits. I'll just grow this to 32 and drop the pad at the end. > uint16_t cs_sel; > uint16_t ss_sel; > uint16_t ds_sel; > uint16_t es_sel; > uint16_t fs_sel; > uint16_t gs_sel; > - uint32_t _pad; > + uint16_t _pad; > }; Tamas
On 02/05/2019 23:40, Tamas K Lengyel wrote: >> @@ -211,13 +212,14 @@ struct vm_event_regs_x86 { >> struct vm_event_x86_selector_reg fs; >> struct vm_event_x86_selector_reg gs; >> uint64_t shadow_gs; >> + uint16_t gdtr_limit; > Whoops, just noticed that limit actually needs 20-bits. I'll just grow > this to 32 and drop the pad at the end. There is no such thing as a GDT or an IDT with a limit beyond 16 bits. (Furthermore, an IDT with a limit beyond 12 bits is just a waste of memory). VT-x performs a consistency check on every vmentry that the VMCS_{G,I}DTR_LIMIT fields are within 16 bits, despite being encoded as 32bit fields. SVM specifies the higher 16 bits as ignored. ~Andrew
On Thu, May 2, 2019 at 5:42 PM Andrew Cooper <andrew.cooper3@citrix.com> wrote: > > On 02/05/2019 23:40, Tamas K Lengyel wrote: > >> @@ -211,13 +212,14 @@ struct vm_event_regs_x86 { > >> struct vm_event_x86_selector_reg fs; > >> struct vm_event_x86_selector_reg gs; > >> uint64_t shadow_gs; > >> + uint16_t gdtr_limit; > > Whoops, just noticed that limit actually needs 20-bits. I'll just grow > > this to 32 and drop the pad at the end. > > There is no such thing as a GDT or an IDT with a limit beyond 16 bits. > (Furthermore, an IDT with a limit beyond 12 bits is just a waste of memory). > > VT-x performs a consistency check on every vmentry that the > VMCS_{G,I}DTR_LIMIT fields are within 16 bits, despite being encoded as > 32bit fields. SVM specifies the higher 16 bits as ignored. > Thanks for the clarification - in that case v2 of this patch is correct. Tamas
diff --git a/xen/arch/x86/vm_event.c b/xen/arch/x86/vm_event.c index 51c3493b1d..52c2a71fa0 100644 --- a/xen/arch/x86/vm_event.c +++ b/xen/arch/x86/vm_event.c @@ -179,6 +179,11 @@ static void vm_event_pack_segment_register(enum x86_segment segment, reg->es_sel = seg.sel; break; + case x86_seg_gdtr: + reg->gdtr_base = seg.base; + reg->gdtr_limit = seg.limit; + break; + default: ASSERT_UNREACHABLE(); } @@ -238,6 +243,7 @@ void vm_event_fill_regs(vm_event_request_t *req) vm_event_pack_segment_register(x86_seg_ss, &req->data.regs.x86); vm_event_pack_segment_register(x86_seg_ds, &req->data.regs.x86); vm_event_pack_segment_register(x86_seg_es, &req->data.regs.x86); + vm_event_pack_segment_register(x86_seg_gdtr, &req->data.regs.x86); req->data.regs.x86.shadow_gs = ctxt.shadow_gs; req->data.regs.x86.dr6 = ctxt.dr6; diff --git a/xen/include/public/vm_event.h b/xen/include/public/vm_event.h index b2bafc0d77..959083d8c4 100644 --- a/xen/include/public/vm_event.h +++ b/xen/include/public/vm_event.h @@ -29,7 +29,7 @@ #include "xen.h" -#define VM_EVENT_INTERFACE_VERSION 0x00000004 +#define VM_EVENT_INTERFACE_VERSION 0x00000005 #if defined(__XEN__) || defined(__XEN_TOOLS__) @@ -198,6 +198,7 @@ struct vm_event_regs_x86 { uint64_t msr_efer; uint64_t msr_star; uint64_t msr_lstar; + uint64_t gdtr_base; uint32_t cs_base; uint32_t ss_base; uint32_t ds_base; @@ -211,13 +212,14 @@ struct vm_event_regs_x86 { struct vm_event_x86_selector_reg fs; struct vm_event_x86_selector_reg gs; uint64_t shadow_gs; + uint16_t gdtr_limit; uint16_t cs_sel; uint16_t ss_sel; uint16_t ds_sel; uint16_t es_sel; uint16_t fs_sel; uint16_t gs_sel; - uint32_t _pad; + uint16_t _pad; }; /*
Receiving this register is useful for introspecting 32-bit Windows when the event being trapped happened while in ring3. Signed-off-by: Tamas K Lengyel <tamas@tklengyel.com> Cc: Razvan Cojocaru <rcojocaru@bitdefender.com> Cc: Tamas K Lengyel <tamas@tklengyel.com> Cc: Jan Beulich <jbeulich@suse.com> Cc: Andrew Cooper <andrew.cooper3@citrix.com> Cc: Wei Liu <wei.liu2@citrix.com> Cc: Roger Pau Monne <roger.pau@citrix.com> --- v2: add gdtr limit --- xen/arch/x86/vm_event.c | 6 ++++++ xen/include/public/vm_event.h | 6 ++++-- 2 files changed, 10 insertions(+), 2 deletions(-)