[PATCH v4 07/15] KVM: s390: get rid of gmap_fault()

Claudio Imbrenda
2025-01-23T14:46:39Z

All gmap page faults are already handled in kvm by the function
kvm_s390_handle_dat_fault(); only few users of gmap_fault remained, all
within kvm.

Convert those calls to use kvm_s390_handle_dat_fault() instead.

Remove gmap_fault() entirely since it has no more users.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
arch/s390/include/asm/gmap.h | 1 -
arch/s390/kvm/intercept.c | 4 +-
arch/s390/mm/gmap.c | 124 -----------------------------------
3 files changed, 2 insertions(+), 127 deletions(-)

diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h
index 3e66f53fe3cc..d4572729269f 100644
--- a/arch/s390/include/asm/gmap.h
+++ b/arch/s390/include/asm/gmap.h
@@ -113,7 +113,6 @@ int gmap_unmap_segment(struct gmap *gmap, unsigned long to, unsigned long len);
unsigned long __gmap_translate(struct gmap *, unsigned long gaddr);
unsigned long gmap_translate(struct gmap *, unsigned long gaddr);
int __gmap_link(struct gmap *gmap, unsigned long gaddr, unsigned long vmaddr);
-int gmap_fault(struct gmap *, unsigned long gaddr, unsigned int fault_flags);
void gmap_discard(struct gmap *, unsigned long from, unsigned long to);
void __gmap_zap(struct gmap *, unsigned long gaddr);
void gmap_unlink(struct mm_struct *, unsigned long *table, unsigned long vmaddr);
diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index 92ae003cd215..83a4b0edf239 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -368,7 +368,7 @@ static int handle_mvpg_pei(struct kvm_vcpu *vcpu)
reg2, &srcaddr, GACC_FETCH, 0);
if (rc)
return kvm_s390_inject_prog_cond(vcpu, rc);
- rc = gmap_fault(vcpu->arch.gmap, srcaddr, 0);
+ rc = kvm_s390_handle_dat_fault(vcpu, srcaddr, 0);
if (rc != 0)
return rc;

@@ -377,7 +377,7 @@ static int handle_mvpg_pei(struct kvm_vcpu *vcpu)
reg1, &dstaddr, GACC_STORE, 0);
if (rc)
return kvm_s390_inject_prog_cond(vcpu, rc);
- rc = gmap_fault(vcpu->arch.gmap, dstaddr, FAULT_FLAG_WRITE);
+ rc = kvm_s390_handle_dat_fault(vcpu, dstaddr, FOLL_WRITE);
if (rc != 0)
return rc;

diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index bfaba7733306..e124fca14737 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -607,130 +607,6 @@ int __gmap_link(struct gmap *gmap, unsigned long gaddr, unsigned long vmaddr)
}
EXPORT_SYMBOL(__gmap_link);

-/**
- * fixup_user_fault_nowait - manually resolve a user page fault without waiting
- * @mm: mm_struct of target mm
- * @address: user address
- * @fault_flags:flags to pass down to handle_mm_fault()
- * @unlocked: did we unlock the mmap_lock while retrying
- *
- * This function behaves similarly to fixup_user_fault(), but it guarantees
- * that the fault will be resolved without waiting. The function might drop
- * and re-acquire the mm lock, in which case @unlocked will be set to true.
- *
- * The guarantee is that the fault is handled without waiting, but the
- * function itself might sleep, due to the lock.
- *
- * Context: Needs to be called with mm->mmap_lock held in read mode, and will
- * return with the lock held in read mode; @unlocked will indicate whether
- * the lock has been dropped and re-acquired. This is the same behaviour as
- * fixup_user_fault().
- *
- * Return: 0 on success, -EAGAIN if the fault cannot be resolved without
- * waiting, -EFAULT if the fault cannot be resolved, -ENOMEM if out of
- * memory.
- */
-static int fixup_user_fault_nowait(struct mm_struct *mm, unsigned long address,
- unsigned int fault_flags, bool *unlocked)
-{
- struct vm_area_struct *vma;
- unsigned int test_flags;
- vm_fault_t fault;
- int rc;
-
- fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT;
- test_flags = fault_flags & FAULT_FLAG_WRITE ? VM_WRITE : VM_READ;
-
- vma = find_vma(mm, address);
- if (unlikely(!vma || address < vma->vm_start))
- return -EFAULT;
- if (unlikely(!(vma->vm_flags & test_flags)))
- return -EFAULT;
-
- fault = handle_mm_fault(vma, address, fault_flags, NULL);
- /* the mm lock has been dropped, take it again */
- if (fault & VM_FAULT_COMPLETED) {
- *unlocked = true;
- mmap_read_lock(mm);
- return 0;
- }
- /* the mm lock has not been dropped */
- if (fault & VM_FAULT_ERROR) {
- rc = vm_fault_to_errno(fault, 0);
- BUG_ON(!rc);
- return rc;
- }
- /* the mm lock has not been dropped because of FAULT_FLAG_RETRY_NOWAIT */
- if (fault & VM_FAULT_RETRY)
- return -EAGAIN;
- /* nothing needed to be done and the mm lock has not been dropped */
- return 0;
-}
-
-/**
- * __gmap_fault - resolve a fault on a guest address
- * @gmap: pointer to guest mapping meta data structure
- * @gaddr: guest address
- * @fault_flags: flags to pass down to handle_mm_fault()
- *
- * Context: Needs to be called with mm->mmap_lock held in read mode. Might
- * drop and re-acquire the lock. Will always return with the lock held.
- */
-static int __gmap_fault(struct gmap *gmap, unsigned long gaddr, unsigned int fault_flags)
-{
- unsigned long vmaddr;
- bool unlocked;
- int rc = 0;
-
-retry:
- unlocked = false;
-
- vmaddr = __gmap_translate(gmap, gaddr);
- if (IS_ERR_VALUE(vmaddr))
- return vmaddr;
-
- if (fault_flags & FAULT_FLAG_RETRY_NOWAIT)
- rc = fixup_user_fault_nowait(gmap->mm, vmaddr, fault_flags, &unlocked);
- else
- rc = fixup_user_fault(gmap->mm, vmaddr, fault_flags, &unlocked);
- if (rc)
- return rc;
- /*
- * In the case that fixup_user_fault unlocked the mmap_lock during
- * fault-in, redo __gmap_translate() to avoid racing with a
- * map/unmap_segment.
- * In particular, __gmap_translate(), fixup_user_fault{,_nowait}(),
- * and __gmap_link() must all be called atomically in one go; if the
- * lock had been dropped in between, a retry is needed.
- */
- if (unlocked)
- goto retry;
-
- return __gmap_link(gmap, gaddr, vmaddr);
-}
-
-/**
- * gmap_fault - resolve a fault on a guest address
- * @gmap: pointer to guest mapping meta data structure
- * @gaddr: guest address
- * @fault_flags: flags to pass down to handle_mm_fault()
- *
- * Returns 0 on success, -ENOMEM for out of memory conditions, -EFAULT if the
- * vm address is already mapped to a different guest segment, and -EAGAIN if
- * FAULT_FLAG_RETRY_NOWAIT was specified and the fault could not be processed
- * immediately.
- */
-int gmap_fault(struct gmap *gmap, unsigned long gaddr, unsigned int fault_flags)
-{
- int rc;
-
- mmap_read_lock(gmap->mm);
- rc = __gmap_fault(gmap, gaddr, fault_flags);
- mmap_read_unlock(gmap->mm);
- return rc;
-}
-EXPORT_SYMBOL_GPL(gmap_fault);
-
/*
* this function is assumed to be called with mmap_lock held
*/
--
2.48.1