Re: [PATCH v12 08/20] KVM: pfncache: allow a cache to be activated with a fixed (userspace) HVA

[Paul Durrant <xadimgnik@xxxxxxxxx>]

On 14/02/2024 16:20, Sean Christopherson wrote:
> On Wed, Feb 14, 2024, Paul Durrant wrote:
> > On 07/02/2024 04:03, Sean Christopherson wrote:
> > > +s390 folks (question on kvm_is_error_gpa() for ya)
> > > But!  kvm_is_error_gpa() already exists, and it very, very sneakily does a memslot
> > > lookup and checks for a valid HVA.
> > >
> > > s390 people, any objection to renaming kvm_is_error_gpa() to something like
> > > kvm_gpa_has_memslot() or kvm_gpa_is_in_memslot()?  s390 is the only code that
> > > uses the existing helper.
> > >
> > > That would both to free up the name to pair with kvm_is_error_hva(), and would
> > > make it obvious what the helper does; I was quite surprised that "error" means
> > > "is covered by a valid memslot".
> >
> > Seemingly no response to this; I'll define a local helper rather than
> > re-working the open-coded tests to check against INVALID_GPA. This can then
> > be trivially replaced if need be.
>
> How about we force a decision with a patch?  This should be easy enough to slot
> in, and I would be quite surprised if s390 is overly attached to kvm_is_error_gpa().

Ok. I'll slot that in.

> From: Sean Christopherson <seanjc@xxxxxxxxxx>
> Date: Wed, 14 Feb 2024 08:05:49 -0800
> Subject: [PATCH] KVM: s390: Refactor kvm_is_error_gpa() into
>   kvm_is_gpa_in_memslot()
>
> Rename kvm_is_error_gpa() to kvm_is_gpa_in_memslot() and invert the
> polarity accordingly in order to (a) free up kvm_is_error_gpa() to match
> with kvm_is_error_{hva,page}(), and (b) to make it more obvious that the
> helper is doing a memslot lookup, i.e. not simply checking for INVALID_GPA.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> ---
>   arch/s390/kvm/diag.c     |  2 +-
>   arch/s390/kvm/gaccess.c  | 14 +++++++-------
>   arch/s390/kvm/kvm-s390.c |  4 ++--
>   arch/s390/kvm/priv.c     |  4 ++--
>   arch/s390/kvm/sigp.c     |  2 +-
>   include/linux/kvm_host.h |  4 ++--
>   6 files changed, 15 insertions(+), 15 deletions(-)
>
> diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
> index 3c65b8258ae6..2a32438e09ce 100644
> --- a/arch/s390/kvm/diag.c
> +++ b/arch/s390/kvm/diag.c
> @@ -102,7 +102,7 @@ static int __diag_page_ref_service(struct kvm_vcpu *vcpu)
>   		    parm.token_addr & 7 || parm.zarch != 0x8000000000000000ULL)
>   			return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
>   
> -		if (kvm_is_error_gpa(vcpu->kvm, parm.token_addr))
> +		if (!kvm_is_gpa_in_memslot(vcpu->kvm, parm.token_addr))
>   			return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
>   
>   		vcpu->arch.pfault_token = parm.token_addr;
> diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
> index 5bfcc50c1a68..415c99649e43 100644
> --- a/arch/s390/kvm/gaccess.c
> +++ b/arch/s390/kvm/gaccess.c
> @@ -664,7 +664,7 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
>   	case ASCE_TYPE_REGION1:	{
>   		union region1_table_entry rfte;
>   
> -		if (kvm_is_error_gpa(vcpu->kvm, ptr))
> +		if (!kvm_is_gpa_in_memslot(vcpu->kvm, ptr))
>   			return PGM_ADDRESSING;
>   		if (deref_table(vcpu->kvm, ptr, &rfte.val))
>   			return -EFAULT;
> @@ -682,7 +682,7 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
>   	case ASCE_TYPE_REGION2: {
>   		union region2_table_entry rste;
>   
> -		if (kvm_is_error_gpa(vcpu->kvm, ptr))
> +		if (!kvm_is_gpa_in_memslot(vcpu->kvm, ptr))
>   			return PGM_ADDRESSING;
>   		if (deref_table(vcpu->kvm, ptr, &rste.val))
>   			return -EFAULT;
> @@ -700,7 +700,7 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
>   	case ASCE_TYPE_REGION3: {
>   		union region3_table_entry rtte;
>   
> -		if (kvm_is_error_gpa(vcpu->kvm, ptr))
> +		if (!kvm_is_gpa_in_memslot(vcpu->kvm, ptr))
>   			return PGM_ADDRESSING;
>   		if (deref_table(vcpu->kvm, ptr, &rtte.val))
>   			return -EFAULT;
> @@ -728,7 +728,7 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
>   	case ASCE_TYPE_SEGMENT: {
>   		union segment_table_entry ste;
>   
> -		if (kvm_is_error_gpa(vcpu->kvm, ptr))
> +		if (!kvm_is_gpa_in_memslot(vcpu->kvm, ptr))
>   			return PGM_ADDRESSING;
>   		if (deref_table(vcpu->kvm, ptr, &ste.val))
>   			return -EFAULT;
> @@ -748,7 +748,7 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
>   		ptr = ste.fc0.pto * (PAGE_SIZE / 2) + vaddr.px * 8;
>   	}
>   	}
> -	if (kvm_is_error_gpa(vcpu->kvm, ptr))
> +	if (!kvm_is_gpa_in_memslot(vcpu->kvm, ptr))
>   		return PGM_ADDRESSING;
>   	if (deref_table(vcpu->kvm, ptr, &pte.val))
>   		return -EFAULT;
> @@ -770,7 +770,7 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
>   		*prot = PROT_TYPE_IEP;
>   		return PGM_PROTECTION;
>   	}
> -	if (kvm_is_error_gpa(vcpu->kvm, raddr.addr))
> +	if (!kvm_is_gpa_in_memslot(vcpu->kvm, raddr.addr))
>   		return PGM_ADDRESSING;
>   	*gpa = raddr.addr;
>   	return 0;
> @@ -957,7 +957,7 @@ static int guest_range_to_gpas(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
>   				return rc;
>   		} else {
>   			gpa = kvm_s390_real_to_abs(vcpu, ga);
> -			if (kvm_is_error_gpa(vcpu->kvm, gpa)) {
> +			if (!kvm_is_gpa_in_memslot(vcpu->kvm, gpa)) {
>   				rc = PGM_ADDRESSING;
>   				prot = PROT_NONE;
>   			}
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index ea63ac769889..3e5a1d7aa81a 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2878,7 +2878,7 @@ static int kvm_s390_vm_mem_op_abs(struct kvm *kvm, struct kvm_s390_mem_op *mop)
>   
>   	srcu_idx = srcu_read_lock(&kvm->srcu);
>   
> -	if (kvm_is_error_gpa(kvm, mop->gaddr)) {
> +	if (!kvm_is_gpa_in_memslot(kvm, mop->gaddr)) {
>   		r = PGM_ADDRESSING;
>   		goto out_unlock;
>   	}
> @@ -2940,7 +2940,7 @@ static int kvm_s390_vm_mem_op_cmpxchg(struct kvm *kvm, struct kvm_s390_mem_op *m
>   
>   	srcu_idx = srcu_read_lock(&kvm->srcu);
>   
> -	if (kvm_is_error_gpa(kvm, mop->gaddr)) {
> +	if (!kvm_is_gpa_in_memslot(kvm, mop->gaddr)) {
>   		r = PGM_ADDRESSING;
>   		goto out_unlock;
>   	}
> diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
> index f875a404a0a0..1be19cc9d73c 100644
> --- a/arch/s390/kvm/priv.c
> +++ b/arch/s390/kvm/priv.c
> @@ -149,7 +149,7 @@ static int handle_set_prefix(struct kvm_vcpu *vcpu)
>   	 * first page, since address is 8k aligned and memory pieces are always
>   	 * at least 1MB aligned and have at least a size of 1MB.
>   	 */
> -	if (kvm_is_error_gpa(vcpu->kvm, address))
> +	if (!kvm_is_gpa_in_memslot(vcpu->kvm, address))
>   		return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
>   
>   	kvm_s390_set_prefix(vcpu, address);
> @@ -464,7 +464,7 @@ static int handle_test_block(struct kvm_vcpu *vcpu)
>   		return kvm_s390_inject_prog_irq(vcpu, &vcpu->arch.pgm);
>   	addr = kvm_s390_real_to_abs(vcpu, addr);
>   
> -	if (kvm_is_error_gpa(vcpu->kvm, addr))
> +	if (!kvm_is_gpa_in_memslot(vcpu->kvm, addr))
>   		return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
>   	/*
>   	 * We don't expect errors on modern systems, and do not care
> diff --git a/arch/s390/kvm/sigp.c b/arch/s390/kvm/sigp.c
> index d9696b530064..55c34cb35428 100644
> --- a/arch/s390/kvm/sigp.c
> +++ b/arch/s390/kvm/sigp.c
> @@ -172,7 +172,7 @@ static int __sigp_set_prefix(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu,
>   	 * first page, since address is 8k aligned and memory pieces are always
>   	 * at least 1MB aligned and have at least a size of 1MB.
>   	 */
> -	if (kvm_is_error_gpa(vcpu->kvm, irq.u.prefix.address)) {
> +	if (!kvm_is_gpa_in_memslot(vcpu->kvm, irq.u.prefix.address)) {
>   		*reg &= 0xffffffff00000000UL;
>   		*reg |= SIGP_STATUS_INVALID_PARAMETER;
>   		return SIGP_CC_STATUS_STORED;
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 7e7fd25b09b3..d175b64488ec 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1788,11 +1788,11 @@ static inline hpa_t pfn_to_hpa(kvm_pfn_t pfn)
>   	return (hpa_t)pfn << PAGE_SHIFT;
>   }
>   
> -static inline bool kvm_is_error_gpa(struct kvm *kvm, gpa_t gpa)
> +static inline bool kvm_is_gpa_in_memslot(struct kvm *kvm, gpa_t gpa)
>   {
>   	unsigned long hva = gfn_to_hva(kvm, gpa_to_gfn(gpa));
>   
> -	return kvm_is_error_hva(hva);
> +	return !kvm_is_error_hva(hva);
>   }
>   
>   enum kvm_stat_kind {
>
> base-commit: 687d8f4c3dea0758afd748968d91288220bbe7e3