On 16.08.21 17:07, 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>
---
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)
I know, "frame" is a beautiful term for "page" -- can we just avoid
using it because we're not using it anywhere else here? :)
What's wrong with "access_guest_page()" ?
+{
+ gfn_t gfn = gpa_to_gfn(gpa);
+ unsigned int offset = offset_in_page(gpa);
+ int rc;
You could turn both const. You might want to consider
reverse-christmas-treeing this.
+
+ 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);
Personally, I prefer passing in pfn + offset instead of a gpa. Also
avoids having to convert back and forth.
+ 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;
Dito, reverse christmas tree might be worth keeping.
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);
What does "seg" mean? I certainly know when "len" means -- which is also
what the function eats.
+ rc = access_guest_frame(vcpu->kvm, mode, gpa, data, seg);
+ len -= seg;
+ gra += seg;
+ data += seg;
}
return rc;
}
--
Thanks,
David / dhildenb
