On 8/16/21 5:07 PM, Janis Schoetterl-Glausch wrote:
> Introduce a helper function for guest frame access.
> Rewrite the calculation of the gpa and the length of the segment
> to be more readable.
>
> Signed-off-by: Janis Schoetterl-Glausch <scgl@xxxxxxxxxxxxx>
Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> ---
> arch/s390/kvm/gaccess.c | 48 +++++++++++++++++++++++++----------------
> 1 file changed, 29 insertions(+), 19 deletions(-)
>
> diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
> index b9f85b2dc053..df83de0843de 100644
> --- a/arch/s390/kvm/gaccess.c
> +++ b/arch/s390/kvm/gaccess.c
> @@ -827,11 +827,26 @@ static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
> return 0;
> }
>
> +static int access_guest_frame(struct kvm *kvm, enum gacc_mode mode, gpa_t gpa,
> + void *data, unsigned int len)
> +{
> + gfn_t gfn = gpa_to_gfn(gpa);
> + unsigned int offset = offset_in_page(gpa);
> + int rc;
> +
> + if (mode == GACC_STORE)
> + rc = kvm_write_guest_page(kvm, gfn, data, offset, len);
> + else
> + rc = kvm_read_guest_page(kvm, gfn, data, offset, len);
> + return rc;
> +}
> +
> 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 int seg;
> unsigned long pages_array[2];
> unsigned long *pages;
> int need_ipte_lock;
> @@ -855,15 +870,12 @@ 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);
> - if (mode == GACC_STORE)
> - rc = kvm_write_guest(vcpu->kvm, gpa, data, _len);
> - else
> - rc = kvm_read_guest(vcpu->kvm, gpa, data, _len);
> - len -= _len;
> - ga += _len;
> - data += _len;
> + gpa = pages[idx] + offset_in_page(ga);
> + seg = min(PAGE_SIZE - offset_in_page(gpa), len);
> + rc = access_guest_frame(vcpu->kvm, mode, gpa, data, seg);
> + len -= seg;
> + ga += seg;
> + data += seg;
> }
> if (need_ipte_lock)
> ipte_unlock(vcpu);
> @@ -875,19 +887,17 @@ 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 long gpa;
> + unsigned int seg;
> int rc = 0;
>
> while (len && !rc) {
> gpa = kvm_s390_real_to_abs(vcpu, gra);
> - _len = min(PAGE_SIZE - (gpa & ~PAGE_MASK), len);
> - if (mode)
> - rc = write_guest_abs(vcpu, gpa, data, _len);
> - else
> - rc = read_guest_abs(vcpu, gpa, data, _len);
> - len -= _len;
> - gra += _len;
> - data += _len;
> + seg = min(PAGE_SIZE - offset_in_page(gpa), len);
> + rc = access_guest_frame(vcpu->kvm, mode, gpa, data, seg);
> + len -= seg;
> + gra += seg;
> + data += seg;
> }
> return rc;
> }
>
