* [PATCH for-4.8] x86/emul: Move CPUID Faulting fault generation into the emulator
@ 2016-10-26 11:09 Andrew Cooper
2016-10-26 12:26 ` Jan Beulich
0 siblings, 1 reply; 5+ messages in thread
From: Andrew Cooper @ 2016-10-26 11:09 UTC (permalink / raw)
To: Xen-devel; +Cc: Andrew Cooper, Wei Liu, Jan Beulich
In hindsight, this is a better position for it, as it avoids opencoding
hvmemul_inject_hw_exception() in hvmemul_cpuid(), and reduces the requirements
on other ops->cpuid() hooks wanting to implement cpuid faulting in the future.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wei.liu2@citrix.com>
---
xen/arch/x86/hvm/emulate.c | 11 -----------
xen/arch/x86/x86_emulate/x86_emulate.c | 10 +++++++++-
2 files changed, 9 insertions(+), 12 deletions(-)
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 70c8d44..5b408f8 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -1556,18 +1556,7 @@ static int hvmemul_cpuid(
*/
if ( ctxt->opcode == X86EMUL_OPC(0x0f, 0xa2) &&
hvm_check_cpuid_faulting(current) )
- {
- struct hvm_emulate_ctxt *hvmemul_ctxt =
- container_of(ctxt, struct hvm_emulate_ctxt, ctxt);
-
- hvmemul_ctxt->exn_pending = 1;
- hvmemul_ctxt->trap.vector = TRAP_gp_fault;
- hvmemul_ctxt->trap.type = X86_EVENTTYPE_HW_EXCEPTION;
- hvmemul_ctxt->trap.error_code = 0;
- hvmemul_ctxt->trap.insn_len = 0;
-
return X86EMUL_EXCEPTION;
- }
hvm_funcs.cpuid_intercept(eax, ebx, ecx, edx);
return X86EMUL_OKAY;
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
index a1821d5..0f8d252 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -5011,8 +5011,16 @@ x86_emulate(
unsigned int eax = _regs.eax, ebx = _regs.ebx;
unsigned int ecx = _regs.ecx, edx = _regs.edx;
fail_if(ops->cpuid == NULL);
- if ( (rc = ops->cpuid(&eax, &ebx, &ecx, &edx, ctxt)) != 0 )
+ switch ( rc = ops->cpuid(&eax, &ebx, &ecx, &edx, ctxt) )
+ {
+ case X86EMUL_OKAY:
+ break;
+ case X86EMUL_EXCEPTION: /* CPUID Faulting active. */
+ generate_exception_if(true, EXC_GP, 0);
+ /* unreachable */
+ default:
goto done;
+ }
_regs.eax = eax; _regs.ebx = ebx;
_regs.ecx = ecx; _regs.edx = edx;
break;
--
2.1.4
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^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH for-4.8] x86/emul: Move CPUID Faulting fault generation into the emulator
2016-10-26 11:09 [PATCH for-4.8] x86/emul: Move CPUID Faulting fault generation into the emulator Andrew Cooper
@ 2016-10-26 12:26 ` Jan Beulich
2016-10-26 12:58 ` [PATCH v2 " Andrew Cooper
0 siblings, 1 reply; 5+ messages in thread
From: Jan Beulich @ 2016-10-26 12:26 UTC (permalink / raw)
To: Andrew Cooper; +Cc: Wei Liu, Xen-devel
>>> On 26.10.16 at 13:09, <andrew.cooper3@citrix.com> wrote:
> --- a/xen/arch/x86/x86_emulate/x86_emulate.c
> +++ b/xen/arch/x86/x86_emulate/x86_emulate.c
> @@ -5011,8 +5011,16 @@ x86_emulate(
> unsigned int eax = _regs.eax, ebx = _regs.ebx;
> unsigned int ecx = _regs.ecx, edx = _regs.edx;
> fail_if(ops->cpuid == NULL);
> - if ( (rc = ops->cpuid(&eax, &ebx, &ecx, &edx, ctxt)) != 0 )
> + switch ( rc = ops->cpuid(&eax, &ebx, &ecx, &edx, ctxt) )
> + {
> + case X86EMUL_OKAY:
> + break;
> + case X86EMUL_EXCEPTION: /* CPUID Faulting active. */
> + generate_exception_if(true, EXC_GP, 0);
> + /* unreachable */
> + default:
> goto done;
> + }
Since this makes the cpuid hook different from other hooks (where
a return of X86EMUL_EXCEPTION means an exception was raised,
not that the emulator should raise one), this should be
accompanied by a comment adjustment in x86_emulate.h. Also I
think this would end up easier to read as
rc = ops->cpuid(&eax, &ebx, &ecx, &edx, ctxt);
generate_exception_if(rc == X86EMUL_EXCEPTION, EXC_GP, 0);
if ( rc != X86EMUL_OKAY )
goto done;
And then I think we should eventually alter X86EMUL_EXCEPTION:
This should be a macro taking both exception type and error code as
arguments, at which point the raising of exceptions could be done
solely by the emulator.
Jan
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^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2 for-4.8] x86/emul: Move CPUID Faulting fault generation into the emulator
2016-10-26 12:26 ` Jan Beulich
@ 2016-10-26 12:58 ` Andrew Cooper
2016-10-26 13:05 ` Wei Liu
2016-10-26 13:40 ` Jan Beulich
0 siblings, 2 replies; 5+ messages in thread
From: Andrew Cooper @ 2016-10-26 12:58 UTC (permalink / raw)
To: Xen-devel; +Cc: Andrew Cooper, Wei Liu, Jan Beulich
In hindsight, this is a better position for it, as it avoids opencoding
hvmemul_inject_hw_exception() in hvmemul_cpuid(), and reduces the requirements
on other ops->cpuid() hooks wanting to implement cpuid faulting in the future.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wei.liu2@citrix.com>
v2:
* Expand the cpuid() hook comment in x86_emulate.h
* Adjust how the exception is generated
---
xen/arch/x86/hvm/emulate.c | 11 -----------
xen/arch/x86/x86_emulate/x86_emulate.c | 5 ++++-
xen/arch/x86/x86_emulate/x86_emulate.h | 7 ++++++-
3 files changed, 10 insertions(+), 13 deletions(-)
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 70c8d44..5b408f8 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -1556,18 +1556,7 @@ static int hvmemul_cpuid(
*/
if ( ctxt->opcode == X86EMUL_OPC(0x0f, 0xa2) &&
hvm_check_cpuid_faulting(current) )
- {
- struct hvm_emulate_ctxt *hvmemul_ctxt =
- container_of(ctxt, struct hvm_emulate_ctxt, ctxt);
-
- hvmemul_ctxt->exn_pending = 1;
- hvmemul_ctxt->trap.vector = TRAP_gp_fault;
- hvmemul_ctxt->trap.type = X86_EVENTTYPE_HW_EXCEPTION;
- hvmemul_ctxt->trap.error_code = 0;
- hvmemul_ctxt->trap.insn_len = 0;
-
return X86EMUL_EXCEPTION;
- }
hvm_funcs.cpuid_intercept(eax, ebx, ecx, edx);
return X86EMUL_OKAY;
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
index a1821d5..2b087e5 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -5011,7 +5011,10 @@ x86_emulate(
unsigned int eax = _regs.eax, ebx = _regs.ebx;
unsigned int ecx = _regs.ecx, edx = _regs.edx;
fail_if(ops->cpuid == NULL);
- if ( (rc = ops->cpuid(&eax, &ebx, &ecx, &edx, ctxt)) != 0 )
+ rc = ops->cpuid(&eax, &ebx, &ecx, &edx, ctxt);
+ generate_exception_if(rc == X86EMUL_EXCEPTION,
+ EXC_GP, 0); /* CPUID Faulting? */
+ if ( rc != X86EMUL_OKAY )
goto done;
_regs.eax = eax; _regs.ebx = ebx;
_regs.ecx = ecx; _regs.edx = edx;
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.h b/xen/arch/x86/x86_emulate/x86_emulate.h
index 641711e..fc8d234 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.h
+++ b/xen/arch/x86/x86_emulate/x86_emulate.h
@@ -352,7 +352,12 @@ struct x86_emulate_ops
int (*wbinvd)(
struct x86_emulate_ctxt *ctxt);
- /* cpuid: Emulate CPUID via given set of EAX-EDX inputs/outputs. */
+ /*
+ * cpuid: Emulate CPUID via given set of EAX-EDX inputs/outputs.
+ *
+ * May return X86EMUL_EXCEPTION, which causes the emulator to inject
+ * #GP[0]. Used to implement CPUID faulting.
+ */
int (*cpuid)(
unsigned int *eax,
unsigned int *ebx,
--
2.1.4
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^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2 for-4.8] x86/emul: Move CPUID Faulting fault generation into the emulator
2016-10-26 12:58 ` [PATCH v2 " Andrew Cooper
@ 2016-10-26 13:05 ` Wei Liu
2016-10-26 13:40 ` Jan Beulich
1 sibling, 0 replies; 5+ messages in thread
From: Wei Liu @ 2016-10-26 13:05 UTC (permalink / raw)
To: Andrew Cooper; +Cc: Wei Liu, Jan Beulich, Xen-devel
On Wed, Oct 26, 2016 at 01:58:02PM +0100, Andrew Cooper wrote:
> In hindsight, this is a better position for it, as it avoids opencoding
> hvmemul_inject_hw_exception() in hvmemul_cpuid(), and reduces the requirements
> on other ops->cpuid() hooks wanting to implement cpuid faulting in the future.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Subject to Jan's review / ack:
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
> ---
> CC: Jan Beulich <JBeulich@suse.com>
> CC: Wei Liu <wei.liu2@citrix.com>
>
> v2:
> * Expand the cpuid() hook comment in x86_emulate.h
> * Adjust how the exception is generated
> ---
> xen/arch/x86/hvm/emulate.c | 11 -----------
> xen/arch/x86/x86_emulate/x86_emulate.c | 5 ++++-
> xen/arch/x86/x86_emulate/x86_emulate.h | 7 ++++++-
> 3 files changed, 10 insertions(+), 13 deletions(-)
>
> diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
> index 70c8d44..5b408f8 100644
> --- a/xen/arch/x86/hvm/emulate.c
> +++ b/xen/arch/x86/hvm/emulate.c
> @@ -1556,18 +1556,7 @@ static int hvmemul_cpuid(
> */
> if ( ctxt->opcode == X86EMUL_OPC(0x0f, 0xa2) &&
> hvm_check_cpuid_faulting(current) )
> - {
> - struct hvm_emulate_ctxt *hvmemul_ctxt =
> - container_of(ctxt, struct hvm_emulate_ctxt, ctxt);
> -
> - hvmemul_ctxt->exn_pending = 1;
> - hvmemul_ctxt->trap.vector = TRAP_gp_fault;
> - hvmemul_ctxt->trap.type = X86_EVENTTYPE_HW_EXCEPTION;
> - hvmemul_ctxt->trap.error_code = 0;
> - hvmemul_ctxt->trap.insn_len = 0;
> -
> return X86EMUL_EXCEPTION;
> - }
>
> hvm_funcs.cpuid_intercept(eax, ebx, ecx, edx);
> return X86EMUL_OKAY;
> diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
> index a1821d5..2b087e5 100644
> --- a/xen/arch/x86/x86_emulate/x86_emulate.c
> +++ b/xen/arch/x86/x86_emulate/x86_emulate.c
> @@ -5011,7 +5011,10 @@ x86_emulate(
> unsigned int eax = _regs.eax, ebx = _regs.ebx;
> unsigned int ecx = _regs.ecx, edx = _regs.edx;
> fail_if(ops->cpuid == NULL);
> - if ( (rc = ops->cpuid(&eax, &ebx, &ecx, &edx, ctxt)) != 0 )
> + rc = ops->cpuid(&eax, &ebx, &ecx, &edx, ctxt);
> + generate_exception_if(rc == X86EMUL_EXCEPTION,
> + EXC_GP, 0); /* CPUID Faulting? */
> + if ( rc != X86EMUL_OKAY )
> goto done;
> _regs.eax = eax; _regs.ebx = ebx;
> _regs.ecx = ecx; _regs.edx = edx;
> diff --git a/xen/arch/x86/x86_emulate/x86_emulate.h b/xen/arch/x86/x86_emulate/x86_emulate.h
> index 641711e..fc8d234 100644
> --- a/xen/arch/x86/x86_emulate/x86_emulate.h
> +++ b/xen/arch/x86/x86_emulate/x86_emulate.h
> @@ -352,7 +352,12 @@ struct x86_emulate_ops
> int (*wbinvd)(
> struct x86_emulate_ctxt *ctxt);
>
> - /* cpuid: Emulate CPUID via given set of EAX-EDX inputs/outputs. */
> + /*
> + * cpuid: Emulate CPUID via given set of EAX-EDX inputs/outputs.
> + *
> + * May return X86EMUL_EXCEPTION, which causes the emulator to inject
> + * #GP[0]. Used to implement CPUID faulting.
> + */
> int (*cpuid)(
> unsigned int *eax,
> unsigned int *ebx,
> --
> 2.1.4
>
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2 for-4.8] x86/emul: Move CPUID Faulting fault generation into the emulator
2016-10-26 12:58 ` [PATCH v2 " Andrew Cooper
2016-10-26 13:05 ` Wei Liu
@ 2016-10-26 13:40 ` Jan Beulich
1 sibling, 0 replies; 5+ messages in thread
From: Jan Beulich @ 2016-10-26 13:40 UTC (permalink / raw)
To: Andrew Cooper; +Cc: Wei Liu, Xen-devel
>>> On 26.10.16 at 14:58, <andrew.cooper3@citrix.com> wrote:
> In hindsight, this is a better position for it, as it avoids opencoding
> hvmemul_inject_hw_exception() in hvmemul_cpuid(), and reduces the
> requirements
> on other ops->cpuid() hooks wanting to implement cpuid faulting in the future.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
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^ permalink raw reply [flat|nested] 5+ messages in thread
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-- links below jump to the message on this page --
2016-10-26 11:09 [PATCH for-4.8] x86/emul: Move CPUID Faulting fault generation into the emulator Andrew Cooper
2016-10-26 12:26 ` Jan Beulich
2016-10-26 12:58 ` [PATCH v2 " Andrew Cooper
2016-10-26 13:05 ` Wei Liu
2016-10-26 13:40 ` Jan Beulich
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