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    SubjectRe: [PATCH v3 1/3] KVM: s390: gaccess: Refactor gpa and length calculation
    On Fri, 26 Nov 2021 17:45:47 +0100
    Janis Schoetterl-Glausch <scgl@linux.ibm.com> wrote:

    > Improve readability by renaming the length variable and
    > not calculating the offset manually.
    >
    > Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
    > Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

    Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

    > ---
    > arch/s390/kvm/gaccess.c | 32 +++++++++++++++++---------------
    > 1 file changed, 17 insertions(+), 15 deletions(-)
    >
    > diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
    > index 6af59c59cc1b..45966fbba182 100644
    > --- a/arch/s390/kvm/gaccess.c
    > +++ b/arch/s390/kvm/gaccess.c
    > @@ -831,8 +831,9 @@ int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, void *data,
    > unsigned long len, enum gacc_mode mode)
    > {
    > psw_t *psw = &vcpu->arch.sie_block->gpsw;
    > - unsigned long _len, nr_pages, gpa, idx;
    > + unsigned long nr_pages, gpa, idx;
    > unsigned long pages_array[2];
    > + unsigned int fragment_len;
    > unsigned long *pages;
    > int need_ipte_lock;
    > union asce asce;
    > @@ -855,15 +856,15 @@ int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, void *data,
    > ipte_lock(vcpu);
    > rc = guest_page_range(vcpu, ga, ar, pages, nr_pages, asce, mode);
    > for (idx = 0; idx < nr_pages && !rc; idx++) {
    > - gpa = *(pages + idx) + (ga & ~PAGE_MASK);
    > - _len = min(PAGE_SIZE - (gpa & ~PAGE_MASK), len);
    > + gpa = pages[idx] + offset_in_page(ga);
    > + fragment_len = min(PAGE_SIZE - offset_in_page(gpa), len);
    > if (mode == GACC_STORE)
    > - rc = kvm_write_guest(vcpu->kvm, gpa, data, _len);
    > + rc = kvm_write_guest(vcpu->kvm, gpa, data, fragment_len);
    > else
    > - rc = kvm_read_guest(vcpu->kvm, gpa, data, _len);
    > - len -= _len;
    > - ga += _len;
    > - data += _len;
    > + rc = kvm_read_guest(vcpu->kvm, gpa, data, fragment_len);
    > + len -= fragment_len;
    > + ga += fragment_len;
    > + data += fragment_len;
    > }
    > if (need_ipte_lock)
    > ipte_unlock(vcpu);
    > @@ -875,19 +876,20 @@ int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, void *data,
    > int access_guest_real(struct kvm_vcpu *vcpu, unsigned long gra,
    > void *data, unsigned long len, enum gacc_mode mode)
    > {
    > - unsigned long _len, gpa;
    > + unsigned int fragment_len;
    > + unsigned long gpa;
    > int rc = 0;
    >
    > while (len && !rc) {
    > gpa = kvm_s390_real_to_abs(vcpu, gra);
    > - _len = min(PAGE_SIZE - (gpa & ~PAGE_MASK), len);
    > + fragment_len = min(PAGE_SIZE - offset_in_page(gpa), len);
    > if (mode)
    > - rc = write_guest_abs(vcpu, gpa, data, _len);
    > + rc = write_guest_abs(vcpu, gpa, data, fragment_len);
    > else
    > - rc = read_guest_abs(vcpu, gpa, data, _len);
    > - len -= _len;
    > - gra += _len;
    > - data += _len;
    > + rc = read_guest_abs(vcpu, gpa, data, fragment_len);
    > + len -= fragment_len;
    > + gra += fragment_len;
    > + data += fragment_len;
    > }
    > return rc;
    > }

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