* [PATCH 0/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"
@ 2018-03-27 2:12 Wanpeng Li
2018-03-27 2:12 ` [PATCH 1/2] KVM: VMX: Introduce handle_ud() Wanpeng Li
2018-03-27 2:12 ` [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction" Wanpeng Li
0 siblings, 2 replies; 12+ messages in thread
From: Wanpeng Li @ 2018-03-27 2:12 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Paolo Bonzini, Radim Krčmář, Andrew Cooper
This patchset introduces a Force Emulation Prefix (ud2a; .ascii "kvm")
for "emulate the next instruction", the codes will be executed by emulator
instead of processor, for testing purposes.
A testcase here:
#include <stdio.h>
#include <string.h>
#define HYPERVISOR_INFO 0x40000000
#define CPUID(idx, eax, ebx, ecx, edx)\
asm volatile (\
"ud2a; .ascii \"kvm\"; 1: cpuid" \
:"=b" (*ebx), "=a" (*eax),"=c" (*ecx), "=d" (*edx)\
:"0"(idx) );
void main()
{
unsigned int eax,ebx,ecx,edx;
char string[13];
CPUID(HYPERVISOR_INFO, &eax, &ebx, &ecx, &edx);
*(unsigned int *)(string+0) = ebx;
*(unsigned int *)(string+4) = ecx;
*(unsigned int *)(string+8) = edx;
string[12] = 0;
if (strncmp(string, "KVMKVMKVM\0\0\0",12) == 0)
printf("kvm guest\n");
else
printf("bare hardware\n");
}
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Wanpeng Li (2):
KVM: VMX: Introduce handle_ud()
KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"
arch/x86/kvm/vmx.c | 38 ++++++++++++++++++++++++++++++--------
1 file changed, 30 insertions(+), 8 deletions(-)
--
2.7.4
^ permalink raw reply [flat|nested] 12+ messages in thread* [PATCH 1/2] KVM: VMX: Introduce handle_ud()
2018-03-27 2:12 [PATCH 0/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction" Wanpeng Li
@ 2018-03-27 2:12 ` Wanpeng Li
2018-03-27 4:38 ` Konrad Rzeszutek Wilk
2018-03-27 2:12 ` [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction" Wanpeng Li
1 sibling, 1 reply; 12+ messages in thread
From: Wanpeng Li @ 2018-03-27 2:12 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Paolo Bonzini, Radim Krčmář, Andrew Cooper
From: Wanpeng Li <wanpengli@tencent.com>
Introduce handle_ud() to handle invalid opcode, this function will be
used by later patches.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
arch/x86/kvm/vmx.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 9bc05f5..0f99833 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6215,6 +6215,18 @@ static int handle_machine_check(struct kvm_vcpu *vcpu)
return 1;
}
+static int handle_ud(struct kvm_vcpu *vcpu)
+{
+ enum emulation_result er;
+
+ er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
+ if (er == EMULATE_USER_EXIT)
+ return 0;
+ if (er != EMULATE_DONE)
+ kvm_queue_exception(vcpu, UD_VECTOR);
+ return 1;
+}
+
static int handle_exception(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -6233,14 +6245,8 @@ static int handle_exception(struct kvm_vcpu *vcpu)
if (is_nmi(intr_info))
return 1; /* already handled by vmx_vcpu_run() */
- if (is_invalid_opcode(intr_info)) {
- er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
- if (er == EMULATE_USER_EXIT)
- return 0;
- if (er != EMULATE_DONE)
- kvm_queue_exception(vcpu, UD_VECTOR);
- return 1;
- }
+ if (is_invalid_opcode(intr_info))
+ return handle_ud(vcpu);
error_code = 0;
if (intr_info & INTR_INFO_DELIVER_CODE_MASK)
--
2.7.4
^ permalink raw reply related [flat|nested] 12+ messages in thread* Re: [PATCH 1/2] KVM: VMX: Introduce handle_ud()
2018-03-27 2:12 ` [PATCH 1/2] KVM: VMX: Introduce handle_ud() Wanpeng Li
@ 2018-03-27 4:38 ` Konrad Rzeszutek Wilk
0 siblings, 0 replies; 12+ messages in thread
From: Konrad Rzeszutek Wilk @ 2018-03-27 4:38 UTC (permalink / raw)
To: Wanpeng Li
Cc: linux-kernel, kvm, Paolo Bonzini, Radim Krčmář,
Andrew Cooper
On Mon, Mar 26, 2018 at 07:12:14PM -0700, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> Introduce handle_ud() to handle invalid opcode, this function will be
> used by later patches.
>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Thank you!
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Cc: Andrew Cooper <andrew.cooper3@citrix.com>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
> arch/x86/kvm/vmx.c | 22 ++++++++++++++--------
> 1 file changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 9bc05f5..0f99833 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -6215,6 +6215,18 @@ static int handle_machine_check(struct kvm_vcpu *vcpu)
> return 1;
> }
>
> +static int handle_ud(struct kvm_vcpu *vcpu)
> +{
> + enum emulation_result er;
> +
> + er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
> + if (er == EMULATE_USER_EXIT)
> + return 0;
> + if (er != EMULATE_DONE)
> + kvm_queue_exception(vcpu, UD_VECTOR);
> + return 1;
> +}
> +
> static int handle_exception(struct kvm_vcpu *vcpu)
> {
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> @@ -6233,14 +6245,8 @@ static int handle_exception(struct kvm_vcpu *vcpu)
> if (is_nmi(intr_info))
> return 1; /* already handled by vmx_vcpu_run() */
>
> - if (is_invalid_opcode(intr_info)) {
> - er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
> - if (er == EMULATE_USER_EXIT)
> - return 0;
> - if (er != EMULATE_DONE)
> - kvm_queue_exception(vcpu, UD_VECTOR);
> - return 1;
> - }
> + if (is_invalid_opcode(intr_info))
> + return handle_ud(vcpu);
>
> error_code = 0;
> if (intr_info & INTR_INFO_DELIVER_CODE_MASK)
> --
> 2.7.4
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"
2018-03-27 2:12 [PATCH 0/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction" Wanpeng Li
2018-03-27 2:12 ` [PATCH 1/2] KVM: VMX: Introduce handle_ud() Wanpeng Li
@ 2018-03-27 2:12 ` Wanpeng Li
2018-03-27 4:40 ` Konrad Rzeszutek Wilk
1 sibling, 1 reply; 12+ messages in thread
From: Wanpeng Li @ 2018-03-27 2:12 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Paolo Bonzini, Radim Krčmář, Andrew Cooper
From: Wanpeng Li <wanpengli@tencent.com>
This patch introduces a Force Emulation Prefix (ud2a; .ascii "kvm") for
"emulate the next instruction", the codes will be executed by emulator
instead of processor, for testing purposes.
A testcase here:
#include <stdio.h>
#include <string.h>
#define HYPERVISOR_INFO 0x40000000
#define CPUID(idx, eax, ebx, ecx, edx)\
asm volatile (\
"ud2a; .ascii \"kvm\"; 1: cpuid" \
:"=b" (*ebx), "=a" (*eax),"=c" (*ecx), "=d" (*edx)\
:"0"(idx) );
void main()
{
unsigned int eax,ebx,ecx,edx;
char string[13];
CPUID(HYPERVISOR_INFO, &eax, &ebx, &ecx, &edx);
*(unsigned int *)(string+0) = ebx;
*(unsigned int *)(string+4) = ecx;
*(unsigned int *)(string+8) = edx;
string[12] = 0;
if (strncmp(string, "KVMKVMKVM\0\0\0",12) == 0)
printf("kvm guest\n");
else
printf("bare hardware\n");
}
Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
arch/x86/kvm/vmx.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 0f99833..90abed8 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -108,6 +108,9 @@ module_param_named(enable_shadow_vmcs, enable_shadow_vmcs, bool, S_IRUGO);
static bool __read_mostly nested = 0;
module_param(nested, bool, S_IRUGO);
+static bool __read_mostly fep = 0;
+module_param(fep, bool, S_IRUGO);
+
static u64 __read_mostly host_xss;
static bool __read_mostly enable_pml = 1;
@@ -6218,8 +6221,21 @@ static int handle_machine_check(struct kvm_vcpu *vcpu)
static int handle_ud(struct kvm_vcpu *vcpu)
{
enum emulation_result er;
+ int emulation_type = EMULTYPE_TRAP_UD;
+
+ if (fep) {
+ char sig[5]; /* ud2; .ascii "kvm" */
+ struct x86_exception e;
+
+ kvm_read_guest_virt(&vcpu->arch.emulate_ctxt,
+ kvm_get_linear_rip(vcpu), sig, sizeof(sig), &e);
+ if (memcmp(sig, "\xf\xbkvm", sizeof(sig)) == 0) {
+ emulation_type = 0;
+ kvm_rip_write(vcpu, kvm_rip_read(vcpu) + sizeof(sig));
+ }
+ }
- er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
+ er = emulate_instruction(vcpu, emulation_type);
if (er == EMULATE_USER_EXIT)
return 0;
if (er != EMULATE_DONE)
--
2.7.4
^ permalink raw reply related [flat|nested] 12+ messages in thread* Re: [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"
2018-03-27 2:12 ` [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction" Wanpeng Li
@ 2018-03-27 4:40 ` Konrad Rzeszutek Wilk
2018-03-27 4:55 ` Konrad Rzeszutek Wilk
2018-03-27 5:09 ` Wanpeng Li
0 siblings, 2 replies; 12+ messages in thread
From: Konrad Rzeszutek Wilk @ 2018-03-27 4:40 UTC (permalink / raw)
To: Wanpeng Li
Cc: linux-kernel, kvm, Paolo Bonzini, Radim Krčmář,
Andrew Cooper
On Mon, Mar 26, 2018 at 07:12:15PM -0700, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> This patch introduces a Force Emulation Prefix (ud2a; .ascii "kvm") for
> "emulate the next instruction", the codes will be executed by emulator
> instead of processor, for testing purposes.
Can you expand a bit ? Why do you want this in KVM in the first place?
Should this be controlled by a boolean parameter?
>
> A testcase here:
>
> #include <stdio.h>
> #include <string.h>
>
> #define HYPERVISOR_INFO 0x40000000
>
> #define CPUID(idx, eax, ebx, ecx, edx)\
> asm volatile (\
> "ud2a; .ascii \"kvm\"; 1: cpuid" \
> :"=b" (*ebx), "=a" (*eax),"=c" (*ecx), "=d" (*edx)\
> :"0"(idx) );
>
> void main()
> {
> unsigned int eax,ebx,ecx,edx;
> char string[13];
>
> CPUID(HYPERVISOR_INFO, &eax, &ebx, &ecx, &edx);
> *(unsigned int *)(string+0) = ebx;
> *(unsigned int *)(string+4) = ecx;
> *(unsigned int *)(string+8) = edx;
>
> string[12] = 0;
> if (strncmp(string, "KVMKVMKVM\0\0\0",12) == 0)
> printf("kvm guest\n");
> else
> printf("bare hardware\n");
> }
>
> Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Cc: Andrew Cooper <andrew.cooper3@citrix.com>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
> arch/x86/kvm/vmx.c | 18 +++++++++++++++++-
> 1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 0f99833..90abed8 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -108,6 +108,9 @@ module_param_named(enable_shadow_vmcs, enable_shadow_vmcs, bool, S_IRUGO);
> static bool __read_mostly nested = 0;
> module_param(nested, bool, S_IRUGO);
>
> +static bool __read_mostly fep = 0;
> +module_param(fep, bool, S_IRUGO);
> +
> static u64 __read_mostly host_xss;
>
> static bool __read_mostly enable_pml = 1;
> @@ -6218,8 +6221,21 @@ static int handle_machine_check(struct kvm_vcpu *vcpu)
> static int handle_ud(struct kvm_vcpu *vcpu)
> {
> enum emulation_result er;
> + int emulation_type = EMULTYPE_TRAP_UD;
> +
> + if (fep) {
> + char sig[5]; /* ud2; .ascii "kvm" */
> + struct x86_exception e;
Don't you want to do = { };
to memset it?
> +
> + kvm_read_guest_virt(&vcpu->arch.emulate_ctxt,
> + kvm_get_linear_rip(vcpu), sig, sizeof(sig), &e);
> + if (memcmp(sig, "\xf\xbkvm", sizeof(sig)) == 0) {
> + emulation_type = 0;
> + kvm_rip_write(vcpu, kvm_rip_read(vcpu) + sizeof(sig));
> + }
> + }
>
> - er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
> + er = emulate_instruction(vcpu, emulation_type);
> if (er == EMULATE_USER_EXIT)
> return 0;
> if (er != EMULATE_DONE)
> --
> 2.7.4
>
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"
2018-03-27 4:40 ` Konrad Rzeszutek Wilk
@ 2018-03-27 4:55 ` Konrad Rzeszutek Wilk
2018-03-27 5:03 ` Wanpeng Li
2018-03-27 5:09 ` Wanpeng Li
1 sibling, 1 reply; 12+ messages in thread
From: Konrad Rzeszutek Wilk @ 2018-03-27 4:55 UTC (permalink / raw)
To: Wanpeng Li
Cc: linux-kernel, kvm, Paolo Bonzini, Radim Krčmář,
Andrew Cooper
On Tue, Mar 27, 2018 at 12:40:20AM -0400, Konrad Rzeszutek Wilk wrote:
> On Mon, Mar 26, 2018 at 07:12:15PM -0700, Wanpeng Li wrote:
> > From: Wanpeng Li <wanpengli@tencent.com>
> >
> > This patch introduces a Force Emulation Prefix (ud2a; .ascii "kvm") for
> > "emulate the next instruction", the codes will be executed by emulator
> > instead of processor, for testing purposes.
>
> Can you expand a bit ? Why do you want this in KVM in the first place?
> Should this be controlled by a boolean parameter?
.. per guest. That is instead of a global one, have a per guest one?
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"
2018-03-27 4:55 ` Konrad Rzeszutek Wilk
@ 2018-03-27 5:03 ` Wanpeng Li
2018-03-27 5:18 ` Konrad Rzeszutek Wilk
0 siblings, 1 reply; 12+ messages in thread
From: Wanpeng Li @ 2018-03-27 5:03 UTC (permalink / raw)
To: Konrad Rzeszutek Wilk
Cc: LKML, kvm, Paolo Bonzini, Radim Krčmář,
Andrew Cooper
2018-03-27 12:55 GMT+08:00 Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>:
> On Tue, Mar 27, 2018 at 12:40:20AM -0400, Konrad Rzeszutek Wilk wrote:
>> On Mon, Mar 26, 2018 at 07:12:15PM -0700, Wanpeng Li wrote:
>> > From: Wanpeng Li <wanpengli@tencent.com>
>> >
>> > This patch introduces a Force Emulation Prefix (ud2a; .ascii "kvm") for
>> > "emulate the next instruction", the codes will be executed by emulator
>> > instead of processor, for testing purposes.
>>
>> Can you expand a bit ? Why do you want this in KVM in the first place?
Please refer to the original discussion(Force Emulation Prefix part).
https://lkml.org/lkml/2018/3/22/220
>> Should this be controlled by a boolean parameter?
>
> .. per guest. That is instead of a global one, have a per guest one?
As Paolo pointed out offline:
> Testing without the hacks being done by emulator.flat (TLB mismatch between instructions and data).
I think a global module is enough for testing.
Regards,
Wanpeng Li
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"
2018-03-27 5:03 ` Wanpeng Li
@ 2018-03-27 5:18 ` Konrad Rzeszutek Wilk
2018-03-27 7:25 ` Paolo Bonzini
0 siblings, 1 reply; 12+ messages in thread
From: Konrad Rzeszutek Wilk @ 2018-03-27 5:18 UTC (permalink / raw)
To: Wanpeng Li
Cc: LKML, kvm, Paolo Bonzini, Radim Krčmář,
Andrew Cooper
On Tue, Mar 27, 2018 at 01:03:15PM +0800, Wanpeng Li wrote:
> 2018-03-27 12:55 GMT+08:00 Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>:
> > On Tue, Mar 27, 2018 at 12:40:20AM -0400, Konrad Rzeszutek Wilk wrote:
> >> On Mon, Mar 26, 2018 at 07:12:15PM -0700, Wanpeng Li wrote:
> >> > From: Wanpeng Li <wanpengli@tencent.com>
> >> >
> >> > This patch introduces a Force Emulation Prefix (ud2a; .ascii "kvm") for
> >> > "emulate the next instruction", the codes will be executed by emulator
> >> > instead of processor, for testing purposes.
> >>
> >> Can you expand a bit ? Why do you want this in KVM in the first place?
>
> Please refer to the original discussion(Force Emulation Prefix part).
> https://lkml.org/lkml/2018/3/22/220
That really should be part massaged in this patch as part of the description.
>
> >> Should this be controlled by a boolean parameter?
> >
> > .. per guest. That is instead of a global one, have a per guest one?
>
> As Paolo pointed out offline:
> > Testing without the hacks being done by emulator.flat (TLB mismatch between instructions and data).
And also this above.
> I think a global module is enough for testing.
If so, perhaps have it wrapped with #ifdef DEBUG?
No need to put code gadgets that won't be utilized 99% of time.
>
> Regards,
> Wanpeng Li
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"
2018-03-27 5:18 ` Konrad Rzeszutek Wilk
@ 2018-03-27 7:25 ` Paolo Bonzini
2018-03-27 7:29 ` Wanpeng Li
0 siblings, 1 reply; 12+ messages in thread
From: Paolo Bonzini @ 2018-03-27 7:25 UTC (permalink / raw)
To: Konrad Rzeszutek Wilk, Wanpeng Li
Cc: LKML, kvm, Radim Krčmář, Andrew Cooper
On 27/03/2018 07:18, Konrad Rzeszutek Wilk wrote:
>> I think a global module is enough for testing.
> If so, perhaps have it wrapped with #ifdef DEBUG?
>
> No need to put code gadgets that won't be utilized 99% of time.
It is going to be used a lot in testing, actually. There are quite a
few emulate.c bugfixes that are hard to test (see for example the
syscall eflags.tf bug that can currently be tested only on Intel) and
having something like this can only improve our coverage.
#ifdef DEBUG is almost always a bad idea, and though I agree that the
commit messages can be improved, I think the module parameter is the way
to go.
Wanpeng, can you also add it to svm.c?
Thanks,
Paolo
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"
2018-03-27 7:25 ` Paolo Bonzini
@ 2018-03-27 7:29 ` Wanpeng Li
0 siblings, 0 replies; 12+ messages in thread
From: Wanpeng Li @ 2018-03-27 7:29 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Konrad Rzeszutek Wilk, LKML, kvm, Radim Krčmář,
Andrew Cooper
2018-03-27 15:25 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
> On 27/03/2018 07:18, Konrad Rzeszutek Wilk wrote:
>>> I think a global module is enough for testing.
>> If so, perhaps have it wrapped with #ifdef DEBUG?
>>
>> No need to put code gadgets that won't be utilized 99% of time.
>
> It is going to be used a lot in testing, actually. There are quite a
> few emulate.c bugfixes that are hard to test (see for example the
> syscall eflags.tf bug that can currently be tested only on Intel) and
> having something like this can only improve our coverage.
>
> #ifdef DEBUG is almost always a bad idea, and though I agree that the
> commit messages can be improved, I think the module parameter is the way
> to go.
>
> Wanpeng, can you also add it to svm.c?
Yeah, thanks for the review. :)
Regards,
Wanpeng Li
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"
2018-03-27 4:40 ` Konrad Rzeszutek Wilk
2018-03-27 4:55 ` Konrad Rzeszutek Wilk
@ 2018-03-27 5:09 ` Wanpeng Li
1 sibling, 0 replies; 12+ messages in thread
From: Wanpeng Li @ 2018-03-27 5:09 UTC (permalink / raw)
To: Konrad Rzeszutek Wilk
Cc: LKML, kvm, Paolo Bonzini, Radim Krčmář,
Andrew Cooper
2018-03-27 12:40 GMT+08:00 Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>:
> On Mon, Mar 26, 2018 at 07:12:15PM -0700, Wanpeng Li wrote:
>> From: Wanpeng Li <wanpengli@tencent.com>
>>
>> This patch introduces a Force Emulation Prefix (ud2a; .ascii "kvm") for
>> "emulate the next instruction", the codes will be executed by emulator
>> instead of processor, for testing purposes.
>
> Can you expand a bit ? Why do you want this in KVM in the first place?
> Should this be controlled by a boolean parameter?
>>
>> A testcase here:
>>
>> #include <stdio.h>
>> #include <string.h>
>>
>> #define HYPERVISOR_INFO 0x40000000
>>
>> #define CPUID(idx, eax, ebx, ecx, edx)\
>> asm volatile (\
>> "ud2a; .ascii \"kvm\"; 1: cpuid" \
>> :"=b" (*ebx), "=a" (*eax),"=c" (*ecx), "=d" (*edx)\
>> :"0"(idx) );
>>
>> void main()
>> {
>> unsigned int eax,ebx,ecx,edx;
>> char string[13];
>>
>> CPUID(HYPERVISOR_INFO, &eax, &ebx, &ecx, &edx);
>> *(unsigned int *)(string+0) = ebx;
>> *(unsigned int *)(string+4) = ecx;
>> *(unsigned int *)(string+8) = edx;
>>
>> string[12] = 0;
>> if (strncmp(string, "KVMKVMKVM\0\0\0",12) == 0)
>> printf("kvm guest\n");
>> else
>> printf("bare hardware\n");
>> }
>>
>> Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: Radim Krčmář <rkrcmar@redhat.com>
>> Cc: Andrew Cooper <andrew.cooper3@citrix.com>
>> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
>> ---
>> arch/x86/kvm/vmx.c | 18 +++++++++++++++++-
>> 1 file changed, 17 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index 0f99833..90abed8 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -108,6 +108,9 @@ module_param_named(enable_shadow_vmcs, enable_shadow_vmcs, bool, S_IRUGO);
>> static bool __read_mostly nested = 0;
>> module_param(nested, bool, S_IRUGO);
>>
>> +static bool __read_mostly fep = 0;
>> +module_param(fep, bool, S_IRUGO);
>> +
>> static u64 __read_mostly host_xss;
>>
>> static bool __read_mostly enable_pml = 1;
>> @@ -6218,8 +6221,21 @@ static int handle_machine_check(struct kvm_vcpu *vcpu)
>> static int handle_ud(struct kvm_vcpu *vcpu)
>> {
>> enum emulation_result er;
>> + int emulation_type = EMULTYPE_TRAP_UD;
>> +
>> + if (fep) {
>> + char sig[5]; /* ud2; .ascii "kvm" */
>> + struct x86_exception e;
>
> Don't you want to do = { };
> to memset it?
sig buffer will be filled by insns which are fetched from guest
memory, so I think not memset is fine.
Regards,
Wanpeng Li
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 1/2] KVM: VMX: Introduce handle_ud()
@ 2018-03-27 7:43 Liran Alon
0 siblings, 0 replies; 12+ messages in thread
From: Liran Alon @ 2018-03-27 7:43 UTC (permalink / raw)
To: kernellwp; +Cc: rkrcmar, pbonzini, linux-kernel, andrew.cooper3, kvm
----- kernellwp@gmail.com wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> Introduce handle_ud() to handle invalid opcode, this function will be
>
> used by later patches.
>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Cc: Andrew Cooper <andrew.cooper3@citrix.com>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
> arch/x86/kvm/vmx.c | 22 ++++++++++++++--------
> 1 file changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 9bc05f5..0f99833 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -6215,6 +6215,18 @@ static int handle_machine_check(struct kvm_vcpu
> *vcpu)
> return 1;
> }
>
> +static int handle_ud(struct kvm_vcpu *vcpu)
> +{
> + enum emulation_result er;
> +
> + er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
> + if (er == EMULATE_USER_EXIT)
> + return 0;
> + if (er != EMULATE_DONE)
> + kvm_queue_exception(vcpu, UD_VECTOR);
> + return 1;
> +}
> +
> static int handle_exception(struct kvm_vcpu *vcpu)
> {
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> @@ -6233,14 +6245,8 @@ static int handle_exception(struct kvm_vcpu
> *vcpu)
> if (is_nmi(intr_info))
> return 1; /* already handled by vmx_vcpu_run() */
>
> - if (is_invalid_opcode(intr_info)) {
> - er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
> - if (er == EMULATE_USER_EXIT)
> - return 0;
> - if (er != EMULATE_DONE)
> - kvm_queue_exception(vcpu, UD_VECTOR);
> - return 1;
> - }
> + if (is_invalid_opcode(intr_info))
> + return handle_ud(vcpu);
>
> error_code = 0;
> if (intr_info & INTR_INFO_DELIVER_CODE_MASK)
> --
> 2.7.4
Reviewed-By: Liran Alon <liran.alon@oracle.com>
^ permalink raw reply [flat|nested] 12+ messages in thread
end of thread, other threads:[~2018-03-27 7:43 UTC | newest]
Thread overview: 12+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2018-03-27 2:12 [PATCH 0/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction" Wanpeng Li
2018-03-27 2:12 ` [PATCH 1/2] KVM: VMX: Introduce handle_ud() Wanpeng Li
2018-03-27 4:38 ` Konrad Rzeszutek Wilk
2018-03-27 2:12 ` [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction" Wanpeng Li
2018-03-27 4:40 ` Konrad Rzeszutek Wilk
2018-03-27 4:55 ` Konrad Rzeszutek Wilk
2018-03-27 5:03 ` Wanpeng Li
2018-03-27 5:18 ` Konrad Rzeszutek Wilk
2018-03-27 7:25 ` Paolo Bonzini
2018-03-27 7:29 ` Wanpeng Li
2018-03-27 5:09 ` Wanpeng Li
-- strict thread matches above, loose matches on Subject: below --
2018-03-27 7:43 [PATCH 1/2] KVM: VMX: Introduce handle_ud() Liran Alon
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