Re: [Xen-devel] [PATCH 12/18 V2]:PVH xen: support invalid op, return PVH features etc...

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 16.03.13 at 01:48, Mukesh Rathor <mukesh.rathor@xxxxxxxxxx> wrote:
> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -459,6 +459,10 @@ static void instruction_done(
>      struct cpu_user_regs *regs, unsigned long eip, unsigned int bpmatch)
>  {
>      regs->eip = eip;
> +
> +    if ( is_pvh_vcpu(current) )
> +        return;

So how would breakpoint matching on emulated instructions work?

> +
>      regs->eflags &= ~X86_EFLAGS_RF;
>      if ( bpmatch || (regs->eflags & X86_EFLAGS_TF) )
>      {
> @@ -475,6 +479,10 @@ static unsigned int check_guest_io_breakpoint(struct 
> vcpu *v,
>      unsigned int width, i, match = 0;
>      unsigned long start;
>  
> +    if ( is_pvh_vcpu(v) ) {
> +        /* for pvh, ctrlreg field is not implemented/used unless we need to 
> */

???

> +        return 0;
> +    }
>      if ( !(v->arch.debugreg[5]) ||
>           !(v->arch.pv_vcpu.ctrlreg[4] & X86_CR4_DE) )
>          return 0;
> @@ -908,14 +916,18 @@ static int emulate_invalid_rdtscp(struct cpu_user_regs 
> *regs)
>  unsigned long emulate_forced_invalid_op(struct cpu_user_regs *regs)
>  {
>      char sig[5], instr[2];
> -    unsigned long eip, rc;
> +    unsigned long eip, rc, addr;
>  
>      eip = regs->eip;
>  
>      /* Check for forced emulation signature: ud2 ; .ascii "xen". */
> -    if ( (rc = copy_from_user(sig, (char *)eip, sizeof(sig))) != 0 )
> +    if ( (rc = raw_copy_from_guest(sig, (char *)eip, sizeof(sig))) != 0 )
>      {
> -        propagate_page_fault(eip + sizeof(sig) - rc, 0);
> +        addr = eip + sizeof(sig) - rc;
> +        if ( is_pvh_vcpu(current) )
> +            return addr;
> +
> +        propagate_page_fault(addr, 0);
>          return EXCRET_fault_fixed;

Returning "addr" here as well as EXCRET_* values, even if you got
this properly separated right now, looks like setting us up for
future problems.

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel