Re: [PATCH] PPC: KVM: Introduce hypervisor call H_GET_TCE

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Fri, 2014-02-21 at 16:31 +0100, Laurent Dufour wrote:
> This fix introduces the H_GET_TCE hypervisor call which is basically the
> reverse of H_PUT_TCE, as defined in the Power Architecture Platform
> Requirements (PAPR).
> 
> The hcall H_GET_TCE is required by the kdump kernel which is calling it to
> retrieve the TCE set up by the panicing kernel.

Alexey, will that work for VFIO ? Or are those patches *still* not
upstream ?

> Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/kvm_ppc.h      |    2 ++
>  arch/powerpc/kvm/book3s_64_vio_hv.c     |   28 ++++++++++++++++++++++++++++
>  arch/powerpc/kvm/book3s_hv_rmhandlers.S |    2 +-
>  3 files changed, 31 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
> index fcd53f0..4096f16 100644
> --- a/arch/powerpc/include/asm/kvm_ppc.h
> +++ b/arch/powerpc/include/asm/kvm_ppc.h
> @@ -129,6 +129,8 @@ extern long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
>  				struct kvm_create_spapr_tce *args);
>  extern long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
>  			     unsigned long ioba, unsigned long tce);
> +extern long kvmppc_h_get_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
> +			     unsigned long ioba);
>  extern struct kvm_rma_info *kvm_alloc_rma(void);
>  extern void kvm_release_rma(struct kvm_rma_info *ri);
>  extern struct page *kvm_alloc_hpt(unsigned long nr_pages);
> diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c
> index 2c25f54..89e96b3 100644
> --- a/arch/powerpc/kvm/book3s_64_vio_hv.c
> +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c
> @@ -75,3 +75,31 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
>  	return H_TOO_HARD;
>  }
>  EXPORT_SYMBOL_GPL(kvmppc_h_put_tce);
> +
> +long kvmppc_h_get_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
> +		      unsigned long ioba)
> +{
> +	struct kvm *kvm = vcpu->kvm;
> +	struct kvmppc_spapr_tce_table *stt;
> +
> +	list_for_each_entry(stt, &kvm->arch.spapr_tce_tables, list) {
> +		if (stt->liobn == liobn) {
> +			unsigned long idx = ioba >> SPAPR_TCE_SHIFT;
> +			struct page *page;
> +			u64 *tbl;
> +
> +			if (ioba >= stt->window_size)
> +				return H_PARAMETER;
> +
> +			page = stt->pages[idx / TCES_PER_PAGE];
> +			tbl = (u64 *)page_address(page);
> +
> +			vcpu->arch.gpr[4] = tbl[idx % TCES_PER_PAGE];
> +			return H_SUCCESS;
> +		}
> +	}
> +
> +	/* Didn't find the liobn, punt it to userspace */
> +	return H_TOO_HARD;
> +}
> +EXPORT_SYMBOL_GPL(kvmppc_h_get_tce);
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index e66d4ec..7d4fe2a 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -1758,7 +1758,7 @@ hcall_real_table:
>  	.long	0		/* 0x10 - H_CLEAR_MOD */
>  	.long	0		/* 0x14 - H_CLEAR_REF */
>  	.long	.kvmppc_h_protect - hcall_real_table
> -	.long	0		/* 0x1c - H_GET_TCE */
> +	.long	.kvmppc_h_get_tce - hcall_real_table
>  	.long	.kvmppc_h_put_tce - hcall_real_table
>  	.long	0		/* 0x24 - H_SET_SPRG0 */
>  	.long	.kvmppc_h_set_dabr - hcall_real_table