The page requested for page-in; sometimes, can have transient
references, and hence cannot migrate immediately. Retry a few times
before returning error.
H_SVM_PAGE_IN interface is enhanced to return H_BUSY if the page is
not in a migratable state.
Cc: Paul Mackerras <pau...@ozlabs.org>
Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Cc: Michael Ellerman <m...@ellerman.id.au>
Cc: Bharata B Rao <bhar...@linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
Cc: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>
Cc: Laurent Dufour <lduf...@linux.ibm.com>
Cc: Thiago Jung Bauermann <bauer...@linux.ibm.com>
Cc: David Gibson <da...@gibson.dropbear.id.au>
Cc: Claudio Carvalho <cclau...@linux.ibm.com>
Cc: kvm-...@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Ram Pai <linux...@us.ibm.com>
---
Documentation/powerpc/ultravisor.rst | 1 +
arch/powerpc/kvm/book3s_hv_uvmem.c | 54 +++++++++++++++++++++---------------
2 files changed, 33 insertions(+), 22 deletions(-)
diff --git a/Documentation/powerpc/ultravisor.rst
b/Documentation/powerpc/ultravisor.rst
index d98fc85..638d1a7 100644
--- a/Documentation/powerpc/ultravisor.rst
+++ b/Documentation/powerpc/ultravisor.rst
@@ -1034,6 +1034,7 @@ Return values
* H_PARAMETER if ``guest_pa`` is invalid.
* H_P2 if ``flags`` is invalid.
* H_P3 if ``order`` of page is invalid.
+ * H_BUSY if ``page`` is not in a state to pagein
Description
~~~~~~~~~~~
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c
b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 12ed52a..c9bdef6 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -843,7 +843,7 @@ unsigned long kvmppc_h_svm_page_in(struct kvm *kvm,
unsigned long gpa,
struct vm_area_struct *vma;
int srcu_idx;
unsigned long gfn = gpa >> page_shift;
- int ret;
+ int ret, repeat_count = REPEAT_COUNT;
if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START))
return H_UNSUPPORTED;
@@ -857,34 +857,44 @@ unsigned long kvmppc_h_svm_page_in(struct kvm *kvm,
unsigned long gpa,
if (flags & H_PAGE_IN_SHARED)
return kvmppc_share_page(kvm, gpa, page_shift);
- ret = H_PARAMETER;
srcu_idx = srcu_read_lock(&kvm->srcu);
- down_write(&kvm->mm->mmap_sem);
- start = gfn_to_hva(kvm, gfn);
- if (kvm_is_error_hva(start))
- goto out;
-
- mutex_lock(&kvm->arch.uvmem_lock);
/* Fail the page-in request of an already paged-in page */
- if (kvmppc_gfn_is_uvmem_pfn(gfn, kvm, NULL))
- goto out_unlock;
+ mutex_lock(&kvm->arch.uvmem_lock);
+ ret = kvmppc_gfn_is_uvmem_pfn(gfn, kvm, NULL);
+ mutex_unlock(&kvm->arch.uvmem_lock);
+ if (ret) {
+ srcu_read_unlock(&kvm->srcu, srcu_idx);
+ return H_PARAMETER;
+ }
- end = start + (1UL << page_shift);
- vma = find_vma_intersection(kvm->mm, start, end);
- if (!vma || vma->vm_start > start || vma->vm_end < end)
- goto out_unlock;
+ do {
+ ret = H_PARAMETER;
+ down_write(&kvm->mm->mmap_sem);
- if (kvmppc_svm_migrate_page(vma, start, end, gpa, kvm, page_shift,
- true))
- goto out_unlock;
+ start = gfn_to_hva(kvm, gfn);
+ if (kvm_is_error_hva(start)) {
+ up_write(&kvm->mm->mmap_sem);
+ break;
+ }
- ret = H_SUCCESS;
+ end = start + (1UL << page_shift);
+ vma = find_vma_intersection(kvm->mm, start, end);
+ if (!vma || vma->vm_start > start || vma->vm_end < end) {
+ up_write(&kvm->mm->mmap_sem);
+ break;
+ }
+
+ mutex_lock(&kvm->arch.uvmem_lock);
+ ret = kvmppc_svm_migrate_page(vma, start, end, gpa, kvm,
page_shift, true);
+ mutex_unlock(&kvm->arch.uvmem_lock);
+
+ up_write(&kvm->mm->mmap_sem);
+ } while (ret == -2 && repeat_count--);
+
+ if (ret == -2)
+ ret = H_BUSY;
-out_unlock:
- mutex_unlock(&kvm->arch.uvmem_lock);
-out:
- up_write(&kvm->mm->mmap_sem);
srcu_read_unlock(&kvm->srcu, srcu_idx);
return ret;
}
--
1.8.3.1
