Re: [Xen-devel] [PATCH 11/17] vmx: nest: L2 tsc

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

At 10:41 +0100 on 22 Apr (1271932883), Qing He wrote:
> L2 TSC needs special handling, either rdtsc exiting is
> turned on or off

Looks OK to me, but I'm a bit behind on some of the recent changes to
TSC handling. 

Tim.

> Signed-off-by: Qing He <qing.he@xxxxxxxxx>
> 
> ---
>  arch/x86/hvm/vmx/nest.c        |   31 +++++++++++++++++++++++++++++++
>  arch/x86/hvm/vmx/vmx.c         |    4 ++++
>  include/asm-x86/hvm/vmx/nest.h |    2 ++
>  3 files changed, 37 insertions(+)
> 
> diff -r 2f9ba6dbbe62 -r 2332586ff957 xen/arch/x86/hvm/vmx/nest.c
> --- a/xen/arch/x86/hvm/vmx/nest.c     Thu Apr 22 22:30:09 2010 +0800
> +++ b/xen/arch/x86/hvm/vmx/nest.c     Thu Apr 22 22:30:09 2010 +0800
> @@ -533,6 +533,18 @@
>   * Nested VMX context switch
>   */
>  
> +u64 vmx_nest_get_tsc_offset(struct vcpu *v)
> +{
> +    u64 offset = 0;
> +    struct vmx_nest_struct *nest = &v->arch.hvm_vmx.nest;
> +
> +    if ( __get_vvmcs(nest->vvmcs, CPU_BASED_VM_EXEC_CONTROL) &
> +         CPU_BASED_USE_TSC_OFFSETING )
> +        offset = __get_vvmcs(nest->vvmcs, TSC_OFFSET);
> +
> +    return offset;
> +}
> +
>  static unsigned long vmcs_gstate_field[] = {
>      /* 16 BITS */
>      GUEST_ES_SELECTOR,
> @@ -715,6 +727,8 @@
>      hvm_set_cr4(__get_vvmcs(nest->vvmcs, GUEST_CR4));
>      hvm_set_cr3(__get_vvmcs(nest->vvmcs, GUEST_CR3));
>  
> +    hvm_funcs.set_tsc_offset(v, v->arch.hvm_vcpu.cache_tsc_offset);
> +
>      vvmcs_to_shadow(nest->vvmcs, VM_ENTRY_INTR_INFO);
>      vvmcs_to_shadow(nest->vvmcs, VM_ENTRY_EXCEPTION_ERROR_CODE);
>      vvmcs_to_shadow(nest->vvmcs, VM_ENTRY_INSTRUCTION_LEN);
> @@ -837,6 +851,8 @@
>      hvm_set_cr4(__get_vvmcs(nest->vvmcs, HOST_CR4));
>      hvm_set_cr3(__get_vvmcs(nest->vvmcs, HOST_CR3));
>  
> +    hvm_funcs.set_tsc_offset(v, v->arch.hvm_vcpu.cache_tsc_offset);
> +
>      __set_vvmcs(nest->vvmcs, VM_ENTRY_INTR_INFO, 0);
>  }
>  
> @@ -1116,6 +1132,21 @@
>  
>          if ( control_bit_for_reason[i].bit & ctrl )
>              nest->vmexit_pending = 1;
> +        else if ( exit_reason == EXIT_REASON_RDTSC )
> +        {
> +            uint64_t tsc;
> +
> +            /*
> +             * rdtsc can't be handled normally in the L0 handler
> +             * if L1 doesn't want it
> +             */
> +            tsc = hvm_get_guest_tsc(v);
> +            tsc += __get_vvmcs(nest->vvmcs, TSC_OFFSET);
> +            regs->eax = (uint32_t)tsc;
> +            regs->edx = (uint32_t)(tsc >> 32);
> +
> +            bypass_l0 = 1;
> +        }
>  
>          break;
>      }
> diff -r 2f9ba6dbbe62 -r 2332586ff957 xen/arch/x86/hvm/vmx/vmx.c
> --- a/xen/arch/x86/hvm/vmx/vmx.c      Thu Apr 22 22:30:09 2010 +0800
> +++ b/xen/arch/x86/hvm/vmx/vmx.c      Thu Apr 22 22:30:09 2010 +0800
> @@ -974,6 +974,10 @@
>  static void vmx_set_tsc_offset(struct vcpu *v, u64 offset)
>  {
>      vmx_vmcs_enter(v);
> +
> +    if ( v->arch.hvm_vcpu.in_nesting )
> +        offset += vmx_nest_get_tsc_offset(v);
> +
>      __vmwrite(TSC_OFFSET, offset);
>  #if defined (__i386__)
>      __vmwrite(TSC_OFFSET_HIGH, offset >> 32);
> diff -r 2f9ba6dbbe62 -r 2332586ff957 xen/include/asm-x86/hvm/vmx/nest.h
> --- a/xen/include/asm-x86/hvm/vmx/nest.h      Thu Apr 22 22:30:09 2010 +0800
> +++ b/xen/include/asm-x86/hvm/vmx/nest.h      Thu Apr 22 22:30:09 2010 +0800
> @@ -69,6 +69,8 @@
>                                              unsigned long value);
>  void vmx_nest_update_exception_bitmap(struct vcpu *v, unsigned long value);
>  
> +u64 vmx_nest_get_tsc_offset(struct vcpu *v);
> +
>  void vmx_nest_idtv_handling(void);
>  
>  int vmx_nest_l2_vmexit_handler(struct cpu_user_regs *regs,
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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