Re: [RFC PATCH] kvmppc: protection keys fix

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

Ram Pai <linuxram@us.ibm.com> writes:

> kvmppc_do_h_enter() hcall, clobbers the high-order two bits of
> the protection key in the lower pte (ptel). Hence
> any pkey  number above 7 fails to behave.
>
> The following patch, preserves the pkey bits.
>
> Signed-off-by: Ram Pai <linuxram@us.ibm.com>
> ---
>  arch/powerpc/include/asm/book3s/64/mmu-hash.h |    1 +
>  arch/powerpc/kvm/book3s_hv_rm_mmu.c           |    2 +-
>  2 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
> index 369f9ff..f07a1c0 100644
> --- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
> +++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
> @@ -109,6 +109,7 @@
>  #define HPTE_R_KEY_BIT2		ASM_CONST(0x0000000000000800)
>  #define HPTE_R_KEY_BIT3		ASM_CONST(0x0000000000000400)
>  #define HPTE_R_KEY_BIT4		ASM_CONST(0x0000000000000200)
> +#define HPTE_R_KEY		(HPTE_R_KEY_LO | HPTE_R_KEY_HI)
>
>  #define HPTE_V_1TB_SEG		ASM_CONST(0x4000000000000000)
>  #define HPTE_V_VRMA_MASK	ASM_CONST(0x4001ffffff000000)
> diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> index ce6f212..d9462ab 100644
> --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> @@ -268,7 +268,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
>  	if (!realmode)
>  		local_irq_restore(irq_flags);
>
> -	ptel &= ~(HPTE_R_PP0 - psize);
> +	ptel &= HPTE_R_KEY | HPTE_R_PP0 | (psize-1);

Is this all needed to get keys to work on kvm ? We use key value 31 and
key value 0 along with absent and invalid hpte config to indicate mmio
and host swapped pages ? Won't that need to be fixed ?


>  	ptel |= pa;
>
>  	if (pa)
> -- 
> 1.7.1

-aneesh