From: Laurent Dufour <ldufour@linux.ibm.com>
To: bharata@linux.ibm.com, linuxram@us.ibm.com
Cc: cclaudio@linux.ibm.com, kvm-ppc@vger.kernel.org,
sathnaga@linux.vnet.ibm.com, aneesh.kumar@linux.ibm.com,
sukadev@linux.ibm.com, linuxppc-dev@lists.ozlabs.org,
bauerman@linux.ibm.com, david@gibson.dropbear.id.au
Subject: [PATCH] KVM: PPC: Book3S HV: rework secure mem slot dropping
Date: Fri, 24 Jul 2020 10:35:27 +0200 [thread overview]
Message-ID: <20200724083527.28027-1-ldufour@linux.ibm.com> (raw)
In-Reply-To: <20200724030337.GC1082478@in.ibm.com>
When a secure memslot is dropped, all the pages backed in the secure
device (aka really backed by secure memory by the Ultravisor)
should be paged out to a normal page. Previously, this was
achieved by triggering the page fault mechanism which is calling
kvmppc_svm_page_out() on each pages.
This can't work when hot unplugging a memory slot because the memory
slot is flagged as invalid and gfn_to_pfn() is then not trying to access
the page, so the page fault mechanism is not triggered.
Since the final goal is to make a call to kvmppc_svm_page_out() it seems
simpler to call directly instead of triggering such a mechanism. This
way kvmppc_uvmem_drop_pages() can be called even when hot unplugging a
memslot.
Since kvmppc_uvmem_drop_pages() is already holding kvm->arch.uvmem_lock,
the call to __kvmppc_svm_page_out() is made. As
__kvmppc_svm_page_out needs the vma pointer to migrate the pages,
the VMA is fetched in a lazy way, to not trigger find_vma() all
the time. In addition, the mmap_sem is held in read mode during
that time, not in write mode since the virual memory layout is not
impacted, and kvm->arch.uvmem_lock prevents concurrent operation
on the secure device.
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
[modified the changelog description]
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
[modified check on the VMA in kvmppc_uvmem_drop_pages]
---
arch/powerpc/kvm/book3s_hv_uvmem.c | 53 ++++++++++++++++++++----------
1 file changed, 36 insertions(+), 17 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index c772e921f769..5dd3e9acdcab 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -632,35 +632,54 @@ static inline int kvmppc_svm_page_out(struct vm_area_struct *vma,
* fault on them, do fault time migration to replace the device PTEs in
* QEMU page table with normal PTEs from newly allocated pages.
*/
-void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
+void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *slot,
struct kvm *kvm, bool skip_page_out)
{
int i;
struct kvmppc_uvmem_page_pvt *pvt;
- unsigned long pfn, uvmem_pfn;
- unsigned long gfn = free->base_gfn;
+ struct page *uvmem_page;
+ struct vm_area_struct *vma = NULL;
+ unsigned long uvmem_pfn, gfn;
+ unsigned long addr, end;
+
+ mmap_read_lock(kvm->mm);
+
+ addr = slot->userspace_addr;
+ end = addr + (slot->npages * PAGE_SIZE);
- for (i = free->npages; i; --i, ++gfn) {
- struct page *uvmem_page;
+ gfn = slot->base_gfn;
+ for (i = slot->npages; i; --i, ++gfn, addr += PAGE_SIZE) {
+
+ /* Fetch the VMA if addr is not in the latest fetched one */
+ if (!vma || addr >= vma->vm_end) {
+ vma = find_vma_intersection(kvm->mm, addr, addr+1);
+ if (!vma) {
+ pr_err("Can't find VMA for gfn:0x%lx\n", gfn);
+ break;
+ }
+ }
mutex_lock(&kvm->arch.uvmem_lock);
- if (!kvmppc_gfn_is_uvmem_pfn(gfn, kvm, &uvmem_pfn)) {
+
+ if (kvmppc_gfn_is_uvmem_pfn(gfn, kvm, &uvmem_pfn)) {
+ uvmem_page = pfn_to_page(uvmem_pfn);
+ pvt = uvmem_page->zone_device_data;
+ pvt->skip_page_out = skip_page_out;
+ pvt->remove_gfn = true;
+
+ if (__kvmppc_svm_page_out(vma, addr, addr + PAGE_SIZE,
+ PAGE_SHIFT, kvm, pvt->gpa))
+ pr_err("Can't page out gpa:0x%lx addr:0x%lx\n",
+ pvt->gpa, addr);
+ } else {
+ /* Remove the shared flag if any */
kvmppc_gfn_remove(gfn, kvm);
- mutex_unlock(&kvm->arch.uvmem_lock);
- continue;
}
- uvmem_page = pfn_to_page(uvmem_pfn);
- pvt = uvmem_page->zone_device_data;
- pvt->skip_page_out = skip_page_out;
- pvt->remove_gfn = true;
mutex_unlock(&kvm->arch.uvmem_lock);
-
- pfn = gfn_to_pfn(kvm, gfn);
- if (is_error_noslot_pfn(pfn))
- continue;
- kvm_release_pfn_clean(pfn);
}
+
+ mmap_read_unlock(kvm->mm);
}
unsigned long kvmppc_h_svm_init_abort(struct kvm *kvm)
--
2.27.0
next prev parent reply other threads:[~2020-07-24 8:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-23 20:07 [PATCH v5 0/7] Migrate non-migrated pages of a SVM Ram Pai
2020-07-23 20:07 ` [PATCH v5 1/7] KVM: PPC: Book3S HV: Fix function definition in book3s_hv_uvmem.c Ram Pai
2020-07-23 20:07 ` [PATCH v5 2/7] KVM: PPC: Book3S HV: Disable page merging in H_SVM_INIT_START Ram Pai
2020-07-23 20:07 ` [PATCH v5 3/7] KVM: PPC: Book3S HV: track the state GFNs associated with secure VMs Ram Pai
2020-07-23 20:07 ` [PATCH v5 4/7] KVM: PPC: Book3S HV: in H_SVM_INIT_DONE, migrate remaining normal-GFNs to secure-GFNs Ram Pai
2020-07-24 4:27 ` Bharata B Rao
2020-07-23 20:07 ` [PATCH v5 5/7] KVM: PPC: Book3S HV: migrate hot plugged memory Ram Pai
2020-07-27 3:55 ` Bharata B Rao
2020-07-23 20:07 ` [PATCH v5 6/7] KVM: PPC: Book3S HV: move kvmppc_svm_page_out up Ram Pai
2020-07-27 3:49 ` Bharata B Rao
2020-07-23 20:07 ` [PATCH v5 7/7] KVM: PPC: Book3S HV: rework secure mem slot dropping Ram Pai
2020-07-24 3:03 ` Bharata B Rao
2020-07-24 7:43 ` Laurent Dufour
2020-07-24 8:35 ` Laurent Dufour [this message]
2020-07-27 3:49 ` [PATCH] " Bharata B Rao
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