Re: [PATCH v4 1/8] KVM: PPC: Ultravisor: Introduce the MSR_S bit

[janani <janani@linux.ibm.com>]

On 2019-06-28 15:08, Claudio Carvalho wrote:
> From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
> 
> The ultravisor processor mode is introduced in POWER platforms that
> supports the Protected Execution Facility (PEF). Ultravisor is higher
> privileged than hypervisor mode.
> 
> In PEF enabled platforms, the MSR_S bit is used to indicate if the
> thread is in secure state. With the MSR_S bit, the privilege state of
> the thread is now determined by MSR_S, MSR_HV and MSR_PR, as follows:
> 
> S   HV  PR
> -----------------------
> 0   x   1   problem
> 1   0   1   problem
> x   x   0   privileged
> x   1   0   hypervisor
> 1   1   0   ultravisor
> 1   1   1   reserved
> 
> The hypervisor doesn't (and can't) run with the MSR_S bit set, but a
> secure guest and the ultravisor firmware do.
> 
> Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
> Signed-off-by: Ram Pai <linuxram@us.ibm.com>
> [ Update the commit message ]
> Signed-off-by: Claudio Carvalho <cclaudio@linux.ibm.com>
  Reviewed-by: Janani Janakiraman <janani@linux.ibm.com>
> ---
>  arch/powerpc/include/asm/reg.h | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/reg.h 
> b/arch/powerpc/include/asm/reg.h
> index 10caa145f98b..39b4c0a519f5 100644
> --- a/arch/powerpc/include/asm/reg.h
> +++ b/arch/powerpc/include/asm/reg.h
> @@ -38,6 +38,7 @@
>  #define MSR_TM_LG	32		/* Trans Mem Available */
>  #define MSR_VEC_LG	25	        /* Enable AltiVec */
>  #define MSR_VSX_LG	23		/* Enable VSX */
> +#define MSR_S_LG	22		/* Secure VM bit */
>  #define MSR_POW_LG	18		/* Enable Power Management */
>  #define MSR_WE_LG	18		/* Wait State Enable */
>  #define MSR_TGPR_LG	17		/* TLB Update registers in use */
> @@ -71,11 +72,13 @@
>  #define MSR_SF		__MASK(MSR_SF_LG)	/* Enable 64 bit mode */
>  #define MSR_ISF		__MASK(MSR_ISF_LG)	/* Interrupt 64b mode valid on 630 
> */
>  #define MSR_HV 		__MASK(MSR_HV_LG)	/* Hypervisor state */
> +#define MSR_S		__MASK(MSR_S_LG)	/* Secure state */
>  #else
>  /* so tests for these bits fail on 32-bit */
>  #define MSR_SF		0
>  #define MSR_ISF		0
>  #define MSR_HV		0
> +#define MSR_S		0
>  #endif
> 
>  /*