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

From: Alexey Kardashevskiy <[email-masked]>
Date: Sat, 22 Feb 2014 11:48:47 +1100

On 02/22/2014 11:28 AM, Alexey Kardashevskiy wrote:
> On 02/22/2014 06:23 AM, Benjamin Herrenschmidt wrote:
>> 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 ?
> 
> Yes.

Oh! My bad, this is _G_et. Not, this won't support VFIO but this should not
break the current "slow" VFIO support in upstream.

>> Or are those patches *still* not
>> upstream ?
> 
> Yes.

This part is still true. I cannot get Alex Graf attention even on much
simpler things for several months.

> 
> 
>>
>>> Signed-off-by: Laurent Dufour <[email-masked]>
>>> ---
>>>  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
>>
>>
>> _______________________________________________
>> Linuxppc-dev mailing list
>> [email-masked]
>> https://lists.ozlabs.org/listinfo/linuxppc-dev
>>
> 
> 

-- 
Alexey Kardashevskiy
IBM OzLabs, LTC Team

e-mail: [email-masked]
notes: Alexey Kardashevskiy/Australia/IBM