* [PATCH v2] arch/x86: Add registers to vm_event
@ 2018-10-17 9:39 Alexandru Stefan ISAILA
2018-10-17 9:49 ` Andrew Cooper
0 siblings, 1 reply; 4+ messages in thread
From: Alexandru Stefan ISAILA @ 2018-10-17 9:39 UTC (permalink / raw)
To: xen-devel
Cc: tamas, wei.liu2, rcojocaru, andrew.cooper3, jbeulich,
Alexandru Stefan ISAILA
This patch adds a couple of regs to the vm_event that are used by
the introspection. The base, limit and ar
bits are compressed into a uint64_t union so as not to enlarge the
vm_event.
Signed-off-by: Alexandru Isaila <aisaila@bitdefender.com>
---
Changes since V1:
- Add helper function for packing
- Change packing logic
- Add sel to x86_selector_reg.
---
xen/arch/x86/vm_event.c | 30 ++++++++++++++++++++++--------
xen/include/public/vm_event.h | 26 ++++++++++++++++++++++----
2 files changed, 44 insertions(+), 12 deletions(-)
diff --git a/xen/arch/x86/vm_event.c b/xen/arch/x86/vm_event.c
index 15de43c3e6..3a29441c84 100644
--- a/xen/arch/x86/vm_event.c
+++ b/xen/arch/x86/vm_event.c
@@ -122,11 +122,25 @@ void vm_event_monitor_next_interrupt(struct vcpu *v)
v->arch.monitor.next_interrupt_enabled = true;
}
+static void vm_event_pack_segment_register(enum x86_segment segment,
+ struct x86_selector_reg *reg)
+{
+ struct segment_register seg;
+
+ hvm_get_segment_register(current, segment, &seg);
+ reg->fields.base = seg.base;
+ if ( seg.g )
+ reg->fields.limit = seg.limit >> 12;
+ else
+ reg->fields.limit = seg.limit;
+ reg->fields.ar = seg.attr;
+ reg->sel = seg.sel;
+}
+
void vm_event_fill_regs(vm_event_request_t *req)
{
#ifdef CONFIG_HVM
const struct cpu_user_regs *regs = guest_cpu_user_regs();
- struct segment_register seg;
struct hvm_hw_cpu ctxt = {};
struct vcpu *curr = current;
@@ -170,14 +184,14 @@ void vm_event_fill_regs(vm_event_request_t *req)
req->data.regs.x86.msr_star = ctxt.msr_star;
req->data.regs.x86.msr_lstar = ctxt.msr_lstar;
- hvm_get_segment_register(curr, x86_seg_fs, &seg);
- req->data.regs.x86.fs_base = seg.base;
-
- hvm_get_segment_register(curr, x86_seg_gs, &seg);
- req->data.regs.x86.gs_base = seg.base;
+ vm_event_pack_segment_register(x86_seg_fs, &req->data.regs.x86.fs);
+ vm_event_pack_segment_register(x86_seg_gs, &req->data.regs.x86.gs);
+ vm_event_pack_segment_register(x86_seg_cs, &req->data.regs.x86.cs);
+ vm_event_pack_segment_register(x86_seg_ss, &req->data.regs.x86.ss);
+ vm_event_pack_segment_register(x86_seg_ds, &req->data.regs.x86.ds);
+ vm_event_pack_segment_register(x86_seg_es, &req->data.regs.x86.es);
- hvm_get_segment_register(curr, x86_seg_cs, &seg);
- req->data.regs.x86.cs_arbytes = seg.attr;
+ req->data.regs.x86.shadow_gs = ctxt.shadow_gs;
#endif
}
diff --git a/xen/include/public/vm_event.h b/xen/include/public/vm_event.h
index 36e3f4685d..705e6f8a1c 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 0x00000003
+#define VM_EVENT_INTERFACE_VERSION 0x00000004
#if defined(__XEN__) || defined(__XEN_TOOLS__)
@@ -157,6 +157,20 @@
#define VM_EVENT_X86_CR4 2
#define VM_EVENT_X86_XCR0 3
+struct __attribute__((__packed__)) x86_selector_reg {
+ uint16_t sel;
+ union
+ {
+ uint64_t bytes;
+ struct
+ {
+ uint64_t base : 32;
+ uint64_t limit : 20;
+ uint64_t ar : 12;
+ } fields;
+ };
+};
+
/*
* Using custom vCPU structs (i.e. not hvm_hw_cpu) for both x86 and ARM
* so as to not fill the vm_event ring buffer too quickly.
@@ -191,9 +205,13 @@ struct vm_event_regs_x86 {
uint64_t msr_efer;
uint64_t msr_star;
uint64_t msr_lstar;
- uint64_t fs_base;
- uint64_t gs_base;
- uint32_t cs_arbytes;
+ struct x86_selector_reg cs;
+ struct x86_selector_reg ss;
+ struct x86_selector_reg ds;
+ struct x86_selector_reg es;
+ struct x86_selector_reg fs;
+ struct x86_selector_reg gs;
+ uint64_t shadow_gs;
uint32_t _pad;
};
--
2.17.1
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* Re: [PATCH v2] arch/x86: Add registers to vm_event
2018-10-17 9:39 [PATCH v2] arch/x86: Add registers to vm_event Alexandru Stefan ISAILA
@ 2018-10-17 9:49 ` Andrew Cooper
2018-10-17 11:11 ` Alexandru Stefan ISAILA
0 siblings, 1 reply; 4+ messages in thread
From: Andrew Cooper @ 2018-10-17 9:49 UTC (permalink / raw)
To: Alexandru Stefan ISAILA, xen-devel; +Cc: tamas, wei.liu2, jbeulich, rcojocaru
On 17/10/18 10:39, Alexandru Stefan ISAILA wrote:
> This patch adds a couple of regs to the vm_event that are used by
> the introspection. The base, limit and ar
> bits are compressed into a uint64_t union so as not to enlarge the
> vm_event.
>
> Signed-off-by: Alexandru Isaila <aisaila@bitdefender.com>
>
> ---
> Changes since V1:
> - Add helper function for packing
> - Change packing logic
> - Add sel to x86_selector_reg.
> ---
> xen/arch/x86/vm_event.c | 30 ++++++++++++++++++++++--------
> xen/include/public/vm_event.h | 26 ++++++++++++++++++++++----
> 2 files changed, 44 insertions(+), 12 deletions(-)
>
> diff --git a/xen/arch/x86/vm_event.c b/xen/arch/x86/vm_event.c
> index 15de43c3e6..3a29441c84 100644
> --- a/xen/arch/x86/vm_event.c
> +++ b/xen/arch/x86/vm_event.c
> @@ -122,11 +122,25 @@ void vm_event_monitor_next_interrupt(struct vcpu *v)
> v->arch.monitor.next_interrupt_enabled = true;
> }
>
> +static void vm_event_pack_segment_register(enum x86_segment segment,
> + struct x86_selector_reg *reg)
> +{
> + struct segment_register seg;
> +
> + hvm_get_segment_register(current, segment, &seg);
> + reg->fields.base = seg.base;
> + if ( seg.g )
> + reg->fields.limit = seg.limit >> 12;
> + else
> + reg->fields.limit = seg.limit;
I know I suggested this, but how about
reg->fields.limit = seg.g ? seg.limit >> 12 : seg.limit;
which is rather shorter, and probably easier to read.
> + reg->fields.ar = seg.attr;
> + reg->sel = seg.sel;
> +}
> +
> void vm_event_fill_regs(vm_event_request_t *req)
> {
> #ifdef CONFIG_HVM
> const struct cpu_user_regs *regs = guest_cpu_user_regs();
> - struct segment_register seg;
> struct hvm_hw_cpu ctxt = {};
> struct vcpu *curr = current;
>
> @@ -170,14 +184,14 @@ void vm_event_fill_regs(vm_event_request_t *req)
> req->data.regs.x86.msr_star = ctxt.msr_star;
> req->data.regs.x86.msr_lstar = ctxt.msr_lstar;
>
> - hvm_get_segment_register(curr, x86_seg_fs, &seg);
> - req->data.regs.x86.fs_base = seg.base;
> -
> - hvm_get_segment_register(curr, x86_seg_gs, &seg);
> - req->data.regs.x86.gs_base = seg.base;
> + vm_event_pack_segment_register(x86_seg_fs, &req->data.regs.x86.fs);
> + vm_event_pack_segment_register(x86_seg_gs, &req->data.regs.x86.gs);
> + vm_event_pack_segment_register(x86_seg_cs, &req->data.regs.x86.cs);
> + vm_event_pack_segment_register(x86_seg_ss, &req->data.regs.x86.ss);
> + vm_event_pack_segment_register(x86_seg_ds, &req->data.regs.x86.ds);
> + vm_event_pack_segment_register(x86_seg_es, &req->data.regs.x86.es);
>
> - hvm_get_segment_register(curr, x86_seg_cs, &seg);
> - req->data.regs.x86.cs_arbytes = seg.attr;
> + req->data.regs.x86.shadow_gs = ctxt.shadow_gs;
> #endif
> }
>
> diff --git a/xen/include/public/vm_event.h b/xen/include/public/vm_event.h
> index 36e3f4685d..705e6f8a1c 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 0x00000003
> +#define VM_EVENT_INTERFACE_VERSION 0x00000004
>
> #if defined(__XEN__) || defined(__XEN_TOOLS__)
>
> @@ -157,6 +157,20 @@
> #define VM_EVENT_X86_CR4 2
> #define VM_EVENT_X86_XCR0 3
>
> +struct __attribute__((__packed__)) x86_selector_reg {
This is a poor choice of name, because you are mixing two different
pieces of information.
sel is a selector value, whereas the union is a segment descriptor
(architecturally speaking).
> + uint16_t sel;
> + union
> + {
> + uint64_t bytes;
> + struct
> + {
> + uint64_t base : 32;
Better known as... ?
> + uint64_t limit : 20;
> + uint64_t ar : 12;
> + } fields;
> + };
> +};
> +
> /*
> * Using custom vCPU structs (i.e. not hvm_hw_cpu) for both x86 and ARM
> * so as to not fill the vm_event ring buffer too quickly.
> @@ -191,9 +205,13 @@ struct vm_event_regs_x86 {
> uint64_t msr_efer;
> uint64_t msr_star;
> uint64_t msr_lstar;
> - uint64_t fs_base;
> - uint64_t gs_base;
What's happened with fs_base and gs_base? You've replaced them with
uint32_t's in x86_selector_reg, but they are 64bit fields in Long mode.
~Andrew
> - uint32_t cs_arbytes;
> + struct x86_selector_reg cs;
> + struct x86_selector_reg ss;
> + struct x86_selector_reg ds;
> + struct x86_selector_reg es;
> + struct x86_selector_reg fs;
> + struct x86_selector_reg gs;
> + uint64_t shadow_gs;
> uint32_t _pad;
> };
>
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* Re: [PATCH v2] arch/x86: Add registers to vm_event
2018-10-17 9:49 ` Andrew Cooper
@ 2018-10-17 11:11 ` Alexandru Stefan ISAILA
2018-10-17 11:12 ` Andrew Cooper
0 siblings, 1 reply; 4+ messages in thread
From: Alexandru Stefan ISAILA @ 2018-10-17 11:11 UTC (permalink / raw)
To: Andrew Cooper, xen-devel; +Cc: tamas, wei.liu2, jbeulich, rcojocaru
On 17.10.2018 12:49, Andrew Cooper wrote:
> On 17/10/18 10:39, Alexandru Stefan ISAILA wrote:
>> This patch adds a couple of regs to the vm_event that are used by
>> the introspection. The base, limit and ar
>> bits are compressed into a uint64_t union so as not to enlarge the
>> vm_event.
>>
>> Signed-off-by: Alexandru Isaila <aisaila@bitdefender.com>
>>
>> ---
>> Changes since V1:
>> - Add helper function for packing
>> - Change packing logic
>> - Add sel to x86_selector_reg.
>> ---
>> xen/arch/x86/vm_event.c | 30 ++++++++++++++++++++++--------
>> xen/include/public/vm_event.h | 26 ++++++++++++++++++++++----
>> 2 files changed, 44 insertions(+), 12 deletions(-)
>>
>> diff --git a/xen/arch/x86/vm_event.c b/xen/arch/x86/vm_event.c
>> index 15de43c3e6..3a29441c84 100644
>> --- a/xen/arch/x86/vm_event.c
>> +++ b/xen/arch/x86/vm_event.c
>> @@ -122,11 +122,25 @@ void vm_event_monitor_next_interrupt(struct vcpu *v)
>> v->arch.monitor.next_interrupt_enabled = true;
>> }
>>
>> +static void vm_event_pack_segment_register(enum x86_segment segment,
>> + struct x86_selector_reg *reg)
>> +{
>> + struct segment_register seg;
>> +
>> + hvm_get_segment_register(current, segment, &seg);
>> + reg->fields.base = seg.base;
>> + if ( seg.g )
>> + reg->fields.limit = seg.limit >> 12;
>> + else
>> + reg->fields.limit = seg.limit;
>
> I know I suggested this, but how about
>
> reg->fields.limit = seg.g ? seg.limit >> 12 : seg.limit;
>
> which is rather shorter, and probably easier to read.
OK, I will revise this on the next version
>
>> + reg->fields.ar = seg.attr;
>> + reg->sel = seg.sel;
>> +}
>> +
>> void vm_event_fill_regs(vm_event_request_t *req)
>> {
>> #ifdef CONFIG_HVM
>> const struct cpu_user_regs *regs = guest_cpu_user_regs();
>> - struct segment_register seg;
>> struct hvm_hw_cpu ctxt = {};
>> struct vcpu *curr = current;
>>
>> @@ -170,14 +184,14 @@ void vm_event_fill_regs(vm_event_request_t *req)
>> req->data.regs.x86.msr_star = ctxt.msr_star;
>> req->data.regs.x86.msr_lstar = ctxt.msr_lstar;
>>
>> - hvm_get_segment_register(curr, x86_seg_fs, &seg);
>> - req->data.regs.x86.fs_base = seg.base;
>> -
>> - hvm_get_segment_register(curr, x86_seg_gs, &seg);
>> - req->data.regs.x86.gs_base = seg.base;
>> + vm_event_pack_segment_register(x86_seg_fs, &req->data.regs.x86.fs);
>> + vm_event_pack_segment_register(x86_seg_gs, &req->data.regs.x86.gs);
>> + vm_event_pack_segment_register(x86_seg_cs, &req->data.regs.x86.cs);
>> + vm_event_pack_segment_register(x86_seg_ss, &req->data.regs.x86.ss);
>> + vm_event_pack_segment_register(x86_seg_ds, &req->data.regs.x86.ds);
>> + vm_event_pack_segment_register(x86_seg_es, &req->data.regs.x86.es);
>>
>> - hvm_get_segment_register(curr, x86_seg_cs, &seg);
>> - req->data.regs.x86.cs_arbytes = seg.attr;
>> + req->data.regs.x86.shadow_gs = ctxt.shadow_gs;
>> #endif
>> }
>>
>> diff --git a/xen/include/public/vm_event.h b/xen/include/public/vm_event.h
>> index 36e3f4685d..705e6f8a1c 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 0x00000003
>> +#define VM_EVENT_INTERFACE_VERSION 0x00000004
>>
>> #if defined(__XEN__) || defined(__XEN_TOOLS__)
>>
>> @@ -157,6 +157,20 @@
>> #define VM_EVENT_X86_CR4 2
>> #define VM_EVENT_X86_XCR0 3
>>
>> +struct __attribute__((__packed__)) x86_selector_reg {
>
> This is a poor choice of name, because you are mixing two different
> pieces of information.
>
> sel is a selector value, whereas the union is a segment descriptor
> (architecturally speaking).
I will take sel out of the structure
>
>> + uint16_t sel;
>> + union
>> + {
>> + uint64_t bytes;
>> + struct
>> + {
>> + uint64_t base : 32;
>
> Better known as... ?
Sorry I don't follow here
>
>> + uint64_t limit : 20;
>> + uint64_t ar : 12;
>> + } fields;
>> + };
>> +};
>> +
>> /*
>> * Using custom vCPU structs (i.e. not hvm_hw_cpu) for both x86 and ARM
>> * so as to not fill the vm_event ring buffer too quickly.
>> @@ -191,9 +205,13 @@ struct vm_event_regs_x86 {
>> uint64_t msr_efer;
>> uint64_t msr_star;
>> uint64_t msr_lstar;
>> - uint64_t fs_base;
>> - uint64_t gs_base;
>
> What's happened with fs_base and gs_base? You've replaced them with
> uint32_t's in x86_selector_reg, but they are 64bit fields in Long mode.
>
> ~Andrew
I will put fs_base and gs_base back in with 64bit
Alex
>
>> - uint32_t cs_arbytes;
>> + struct x86_selector_reg cs;
>> + struct x86_selector_reg ss;
>> + struct x86_selector_reg ds;
>> + struct x86_selector_reg es;
>> + struct x86_selector_reg fs;
>> + struct x86_selector_reg gs;
>> + uint64_t shadow_gs;
>> uint32_t _pad;
>> };
>>
>
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* Re: [PATCH v2] arch/x86: Add registers to vm_event
2018-10-17 11:11 ` Alexandru Stefan ISAILA
@ 2018-10-17 11:12 ` Andrew Cooper
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Cooper @ 2018-10-17 11:12 UTC (permalink / raw)
To: Alexandru Stefan ISAILA, xen-devel; +Cc: tamas, wei.liu2, jbeulich, rcojocaru
On 17/10/18 12:11, Alexandru Stefan ISAILA wrote:
>
>>> + uint16_t sel;
>>> + union
>>> + {
>>> + uint64_t bytes;
>>> + struct
>>> + {
>>> + uint64_t base : 32;
>> Better known as... ?
> Sorry I don't follow here
An aligned 32-bit bitfield of a uin64_t is more commonly known as uint32_t.
:)
~Andrew
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2018-10-17 9:39 [PATCH v2] arch/x86: Add registers to vm_event Alexandru Stefan ISAILA
2018-10-17 9:49 ` Andrew Cooper
2018-10-17 11:11 ` Alexandru Stefan ISAILA
2018-10-17 11:12 ` Andrew Cooper
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