Commit 6eb84e13 authored by Claudio Imbrenda's avatar Claudio Imbrenda
Browse files

KVM: s390: get rid of gmap_fault() 



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.

Acked-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Reviewed-by: default avatarChristoph Schlameuss <schlameuss@linux.ibm.com>
Link: https://lore.kernel.org/r/20250123144627.312456-8-imbrenda@linux.ibm.com


Signed-off-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20250123144627.312456-8-imbrenda@linux.ibm.com>
parent 3762e905

arch/s390/include/asm/gmap.h

+0 −1
Original line number Diff line number Diff line
@@ -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);

arch/s390/kvm/intercept.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

arch/s390/mm/gmap.c

+0 −124
Original line number Diff line number Diff line
@@ -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

 */