Re: [PATCH] kvm/x86: add support for MONITOR_TRAP_FLAG

[Jan Kiszka]

On 2015-07-05 19:08, Mihai DonÈu wrote:
> Allow a nested hypervisor to single step its guests.
> 
> Signed-off-by: Mihai DonÈu <mihai.dontu@xxxxxxxxx>
> 
> ---
> 
> This patch applies on top of current linux-next.
> ---
>  arch/x86/include/asm/vmx.h      |  1 +
>  arch/x86/include/uapi/asm/vmx.h |  2 ++
>  arch/x86/kvm/vmx.c              | 10 +++++++++-
>  3 files changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> index da772ed..9299ae5 100644
> --- a/arch/x86/include/asm/vmx.h
> +++ b/arch/x86/include/asm/vmx.h
> @@ -47,6 +47,7 @@
>  #define CPU_BASED_MOV_DR_EXITING                0x00800000
>  #define CPU_BASED_UNCOND_IO_EXITING             0x01000000
>  #define CPU_BASED_USE_IO_BITMAPS                0x02000000
> +#define CPU_BASED_MONITOR_TRAP_FLAG             0x08000000
>  #define CPU_BASED_USE_MSR_BITMAPS               0x10000000
>  #define CPU_BASED_MONITOR_EXITING               0x20000000
>  #define CPU_BASED_PAUSE_EXITING                 0x40000000
> diff --git a/arch/x86/include/uapi/asm/vmx.h b/arch/x86/include/uapi/asm/vmx.h
> index 1fe9218..37fee27 100644
> --- a/arch/x86/include/uapi/asm/vmx.h
> +++ b/arch/x86/include/uapi/asm/vmx.h
> @@ -58,6 +58,7 @@
>  #define EXIT_REASON_INVALID_STATE       33
>  #define EXIT_REASON_MSR_LOAD_FAIL       34
>  #define EXIT_REASON_MWAIT_INSTRUCTION   36
> +#define EXIT_REASON_MONITOR_TRAP_FLAG   37
>  #define EXIT_REASON_MONITOR_INSTRUCTION 39
>  #define EXIT_REASON_PAUSE_INSTRUCTION   40
>  #define EXIT_REASON_MCE_DURING_VMENTRY  41
> @@ -106,6 +107,7 @@
>  	{ EXIT_REASON_MSR_READ,              "MSR_READ" }, \
>  	{ EXIT_REASON_MSR_WRITE,             "MSR_WRITE" }, \
>  	{ EXIT_REASON_MWAIT_INSTRUCTION,     "MWAIT_INSTRUCTION" }, \
> +	{ EXIT_REASON_MONITOR_TRAP_FLAG,     "MONITOR_TRAP_FLAG" }, \
>  	{ EXIT_REASON_MONITOR_INSTRUCTION,   "MONITOR_INSTRUCTION" }, \
>  	{ EXIT_REASON_PAUSE_INSTRUCTION,     "PAUSE_INSTRUCTION" }, \
>  	{ EXIT_REASON_MCE_DURING_VMENTRY,    "MCE_DURING_VMENTRY" }, \
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index e856dd5..6d7c650 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -2443,7 +2443,7 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
>  		CPU_BASED_CR8_LOAD_EXITING | CPU_BASED_CR8_STORE_EXITING |
>  #endif
>  		CPU_BASED_MOV_DR_EXITING | CPU_BASED_UNCOND_IO_EXITING |
> -		CPU_BASED_USE_IO_BITMAPS | CPU_BASED_MONITOR_EXITING |
> +		CPU_BASED_USE_IO_BITMAPS | CPU_BASED_MONITOR_TRAP_FLAG | CPU_BASED_MONITOR_EXITING |

Overlong line.

>  		CPU_BASED_RDPMC_EXITING | CPU_BASED_RDTSC_EXITING |
>  		CPU_BASED_PAUSE_EXITING | CPU_BASED_TPR_SHADOW |
>  		CPU_BASED_ACTIVATE_SECONDARY_CONTROLS;
> @@ -6246,6 +6246,11 @@ static int handle_mwait(struct kvm_vcpu *vcpu)
>  	return handle_nop(vcpu);
>  }
>  
> +static int handle_monitor_trap(struct kvm_vcpu *vcpu)
> +{
> +	return 1;
> +}
> +
>  static int handle_monitor(struct kvm_vcpu *vcpu)
>  {
>  	printk_once(KERN_WARNING "kvm: MONITOR instruction emulated as NOP!\n");
> @@ -7282,6 +7287,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
>  	[EXIT_REASON_EPT_MISCONFIG]           = handle_ept_misconfig,
>  	[EXIT_REASON_PAUSE_INSTRUCTION]       = handle_pause,
>  	[EXIT_REASON_MWAIT_INSTRUCTION]	      = handle_mwait,
> +	[EXIT_REASON_MONITOR_TRAP_FLAG]       = handle_monitor_trap,
>  	[EXIT_REASON_MONITOR_INSTRUCTION]     = handle_monitor,
>  	[EXIT_REASON_INVEPT]                  = handle_invept,
>  	[EXIT_REASON_INVVPID]                 = handle_invvpid,
> @@ -7542,6 +7548,8 @@ static bool nested_vmx_exit_handled(struct kvm_vcpu *vcpu)
>  		return true;
>  	case EXIT_REASON_MWAIT_INSTRUCTION:
>  		return nested_cpu_has(vmcs12, CPU_BASED_MWAIT_EXITING);
> +	case EXIT_REASON_MONITOR_TRAP_FLAG:
> +		return nested_cpu_has(vmcs12, CPU_BASED_MONITOR_TRAP_FLAG);
>  	case EXIT_REASON_MONITOR_INSTRUCTION:
>  		return nested_cpu_has(vmcs12, CPU_BASED_MONITOR_EXITING);
>  	case EXIT_REASON_PAUSE_INSTRUCTION:
> 

Looks OK otherwise. If you fix up the style thing, you may add my

Reviewed-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>

Jan

-- 
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux
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