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@vger.kernel.org Signed-off-by: Claudio Imbrenda imbrenda@linux.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 {