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Message-ID: <66d0da8a-a43d-1f04-8fa0-dec5e49b56b7@linux.ibm.com>
Date: Tue, 19 Jan 2021 15:59:36 +0100
From: Janosch Frank <frankja@...ux.ibm.com>
To: Claudio Imbrenda <imbrenda@...ux.ibm.com>,
linux-kernel@...r.kernel.org
Cc: borntraeger@...ibm.com, david@...hat.com, kvm@...r.kernel.org,
linux-s390@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v1 2/4] s390/kvm: extend guest_translate for MVPG
interpretation
On 12/18/20 3:18 PM, Claudio Imbrenda wrote:
> Extend guest_translate to optionally return the address of the guest
> DAT table which caused the exception, and change the return value to int.
>
> Also return the appropriate values in the low order bits of the address
> indicating protection or EDAT.
>
> Cc: stable@...r.kernel.org
> Signed-off-by: Claudio Imbrenda <imbrenda@...ux.ibm.com>
> ---
> arch/s390/kvm/gaccess.c | 33 ++++++++++++++++++++++++++++-----
> 1 file changed, 28 insertions(+), 5 deletions(-)
>
> diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
> index 6d6b57059493..8e256a233583 100644
> --- a/arch/s390/kvm/gaccess.c
> +++ b/arch/s390/kvm/gaccess.c
> @@ -598,6 +598,10 @@ static int deref_table(struct kvm *kvm, unsigned long gpa, unsigned long *val)
> * @asce: effective asce
> * @mode: indicates the access mode to be used
> * @prot: returns the type for protection exceptions
> + * @entryptr: returns the physical address of the last DAT table entry
> + * processed, additionally setting a few flags in the lower bits
> + * to indicate whether a translation exception or a protection
> + * exception were encountered during the address translation.
I'd much rather have another argument pointer than fusing the address
and the status bits. Or we could make prot a struct and add your status
bits in.
> *
> * Translate a guest virtual address into a guest absolute address by means
> * of dynamic address translation as specified by the architecture.
> @@ -611,9 +615,10 @@ static int deref_table(struct kvm *kvm, unsigned long gpa, unsigned long *val)
> * the returned value is the program interruption code as defined
> * by the architecture
> */
> -static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
> - unsigned long *gpa, const union asce asce,
> - enum gacc_mode mode, enum prot_type *prot)
> +static int guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
> + unsigned long *gpa, const union asce asce,
> + enum gacc_mode mode, enum prot_type *prot,
> + unsigned long *entryptr)
> {
> union vaddress vaddr = {.addr = gva};
> union raddress raddr = {.addr = gva};
> @@ -628,6 +633,8 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
> edat1 = ctlreg0.edat && test_kvm_facility(vcpu->kvm, 8);
> edat2 = edat1 && test_kvm_facility(vcpu->kvm, 78);
> iep = ctlreg0.iep && test_kvm_facility(vcpu->kvm, 130);
> + if (entryptr)
> + *entryptr = 0;
> if (asce.r)
> goto real_address;
> ptr = asce.origin * PAGE_SIZE;
> @@ -667,6 +674,8 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
> return PGM_ADDRESSING;
> if (deref_table(vcpu->kvm, ptr, &rfte.val))
> return -EFAULT;
> + if (entryptr)
> + *entryptr = ptr;
> if (rfte.i)
> return PGM_REGION_FIRST_TRANS;
> if (rfte.tt != TABLE_TYPE_REGION1)
> @@ -685,6 +694,8 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
> return PGM_ADDRESSING;
> if (deref_table(vcpu->kvm, ptr, &rste.val))
> return -EFAULT;
> + if (entryptr)
> + *entryptr = ptr;
> if (rste.i)
> return PGM_REGION_SECOND_TRANS;
> if (rste.tt != TABLE_TYPE_REGION2)
> @@ -703,6 +714,8 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
> return PGM_ADDRESSING;
> if (deref_table(vcpu->kvm, ptr, &rtte.val))
> return -EFAULT;
> + if (entryptr)
> + *entryptr = ptr;
> if (rtte.i)
> return PGM_REGION_THIRD_TRANS;
> if (rtte.tt != TABLE_TYPE_REGION3)
> @@ -713,6 +726,8 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
> dat_protection |= rtte.fc1.p;
> iep_protection = rtte.fc1.iep;
> raddr.rfaa = rtte.fc1.rfaa;
> + if (entryptr)
> + *entryptr |= dat_protection ? 6 : 4;
Magic constants are magic
> goto absolute_address;
> }
> if (vaddr.sx01 < rtte.fc0.tf)
> @@ -731,6 +746,8 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
> return PGM_ADDRESSING;
> if (deref_table(vcpu->kvm, ptr, &ste.val))
> return -EFAULT;
> + if (entryptr)
> + *entryptr = ptr;
> if (ste.i)
> return PGM_SEGMENT_TRANSLATION;
> if (ste.tt != TABLE_TYPE_SEGMENT)
> @@ -741,6 +758,8 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
> dat_protection |= ste.fc1.p;
> iep_protection = ste.fc1.iep;
> raddr.sfaa = ste.fc1.sfaa;
> + if (entryptr)
> + *entryptr |= dat_protection ? 6 : 4;
> goto absolute_address;
> }
> dat_protection |= ste.fc0.p;
> @@ -751,10 +770,14 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
> return PGM_ADDRESSING;
> if (deref_table(vcpu->kvm, ptr, &pte.val))
> return -EFAULT;
> + if (entryptr)
> + *entryptr = ptr;
> if (pte.i)
> return PGM_PAGE_TRANSLATION;
> if (pte.z)
> return PGM_TRANSLATION_SPEC;
> + if (entryptr && dat_protection)
> + *entryptr |= 2;
> dat_protection |= pte.p;
> iep_protection = pte.iep;
> raddr.pfra = pte.pfra;
> @@ -810,7 +833,7 @@ static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
> PROT_TYPE_LA);
> ga &= PAGE_MASK;
> if (psw_bits(*psw).dat) {
> - rc = guest_translate(vcpu, ga, pages, asce, mode, &prot);
> + rc = guest_translate(vcpu, ga, pages, asce, mode, &prot, NULL);
> if (rc < 0)
> return rc;
> } else {
> @@ -920,7 +943,7 @@ int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
> }
>
> if (psw_bits(*psw).dat && !asce.r) { /* Use DAT? */
> - rc = guest_translate(vcpu, gva, gpa, asce, mode, &prot);
> + rc = guest_translate(vcpu, gva, gpa, asce, mode, &prot, NULL);
> if (rc > 0)
> return trans_exc(vcpu, rc, gva, 0, mode, prot);
> } else {
>
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