Re: [Xen-devel] [PATCH 3/6] x86: Handle the Xen MSRs via the new guest_{rd, wr}msr() infrastructure

[Jan Beulich]

>>> On 26.02.18 at 18:35,  wrote:
> --- a/xen/arch/x86/msr.c
> +++ b/xen/arch/x86/msr.c
> @@ -183,6 +183,10 @@ int guest_rdmsr(const struct vcpu *v, uint32_t msr, 
> uint64_t *val)
>  }
>  
>  /* Fallthrough. */
> +case 0x4200 ... 0x42ff:

These again want to have #define-s added.

> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -776,29 +776,26 @@ static void do_trap(struct cpu_user_regs *regs)
>trapnr, trapstr(trapnr), regs->error_code);
>  }
>  
> -/* Returns 0 if not handled, and non-0 for success. */
> -int rdmsr_hypervisor_regs(uint32_t idx, uint64_t *val)
> +int guest_rdmsr_xen(const struct vcpu *v, uint32_t idx, uint64_t *val)
>  {
> -struct domain *d = current->domain;
> +const struct domain *d = v->domain;
>  /* Optionally shift out of the way of Viridian architectural MSRs. */
>  uint32_t base = is_viridian_domain(d) ? 0x4200 : 0x4000;
>  
>  switch ( idx - base )
>  {
>  case 0: /* Write hypercall page MSR.  Read as zero. */
> -{
>  *val = 0;
> -return 1;
> -}
> -}
> +return X86EMUL_OKAY;
>  
> -return 0;
> +default:
> +return X86EMUL_EXCEPTION;
> +}
>  }

Could I talk you into adjusting the code to have a "return" at the
end of the function, e.g. by dropping the default case? Also on
the write path then?

With at least the #define-s added,
Reviewed-by: Jan Beulich 

Jan


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Re: [Xen-devel] [PATCH 3/6] x86: Handle the Xen MSRs via the new guest_{rd, wr}msr() infrastructure

[Roger Pau Monné]

On Mon, Feb 26, 2018 at 05:35:16PM +, Andrew Cooper wrote:
> Dispatch from the guest_{rd,wr}msr() functions, after falling through from the
> !is_viridian_domain() case.
> 
> Rename {rd,wr}msr_hypervisor_regs() to guest_{rd,wr}msr_xen() for consistency,
> and because the _regs suffix isn't very appropriate.
> 
> Update them to take a vcpu pointer rather than presuming that they act on
> current, and switch to using X86EMUL_* return values.
> 
> Signed-off-by: Andrew Cooper 

Reviewed-by: Roger Pau Monné 

> diff --git a/xen/arch/x86/msr.c b/xen/arch/x86/msr.c
> index 2ff9361..9f20fd8 100644
> --- a/xen/arch/x86/msr.c
> +++ b/xen/arch/x86/msr.c
> @@ -183,6 +183,10 @@ int guest_rdmsr(const struct vcpu *v, uint32_t msr, 
> uint64_t *val)
>  }
>  
>  /* Fallthrough. */
> +case 0x4200 ... 0x42ff:
> +ret = guest_rdmsr_xen(v, msr, val);
> +goto out;
> +
>  default:
>  return X86EMUL_UNHANDLEABLE;
>  }
> @@ -274,6 +278,10 @@ int guest_wrmsr(struct vcpu *v, uint32_t msr, uint64_t 
> val)
>  }
>  
>  /* Fallthrough. */
> +case 0x4200 ... 0x42ff:

A define would be better in order to prevent this two values from
getting out of sync with the ones in rdmsr maybe.

Thanks, Roger.

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Re: [Xen-devel] [PATCH 3/6] x86: Handle the Xen MSRs via the new guest_{rd, wr}msr() infrastructure

[Tian, Kevin]

> From: Andrew Cooper [mailto:andrew.coop...@citrix.com]
> Sent: Tuesday, February 27, 2018 1:35 AM
> 
> Dispatch from the guest_{rd,wr}msr() functions, after falling through from
> the
> !is_viridian_domain() case.
> 
> Rename {rd,wr}msr_hypervisor_regs() to guest_{rd,wr}msr_xen() for
> consistency,
> and because the _regs suffix isn't very appropriate.
> 
> Update them to take a vcpu pointer rather than presuming that they act on
> current, and switch to using X86EMUL_* return values.
> 
> Signed-off-by: Andrew Cooper 

Reviewed-by: Kevin Tian 
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Re: [Xen-devel] [PATCH 3/6] x86: Handle the Xen MSRs via the new guest_{rd, wr}msr() infrastructure

[Boris Ostrovsky]

On 02/26/2018 12:35 PM, Andrew Cooper wrote:
> Dispatch from the guest_{rd,wr}msr() functions, after falling through from the
> !is_viridian_domain() case.
>
> Rename {rd,wr}msr_hypervisor_regs() to guest_{rd,wr}msr_xen() for consistency,
> and because the _regs suffix isn't very appropriate.
>
> Update them to take a vcpu pointer rather than presuming that they act on
> current, and switch to using X86EMUL_* return values.
>
> Signed-off-by: Andrew Cooper 
> ---
> CC: Jan Beulich 
> CC: Jun Nakajima 
> CC: Paul Durrant 
> CC: Kevin Tian 
> CC: Boris Ostrovsky 
> CC: Suravee Suthikulpanit 
> CC: Wei Liu 
> CC: Roger Pau Monné 
> CC: Sergey Dyasli 
> ---
>  xen/arch/x86/hvm/svm/svm.c  | 25 -
>  xen/arch/x86/hvm/vmx/vmx.c  | 24 
>  xen/arch/x86/msr.c  |  8 
>  xen/arch/x86/pv/emul-priv-op.c  |  6 --
>  xen/arch/x86/traps.c| 33 -
>  xen/include/asm-x86/processor.h |  4 ++--
>  6 files changed, 34 insertions(+), 66 deletions(-)


Reviewed-by: Boris Ostrovsky 

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