From: Ram Pai <linuxram@us.ibm.com>
To: kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Cc: ldufour@linux.ibm.com, linuxram@us.ibm.com,
cclaudio@linux.ibm.com, bharata@linux.ibm.com,
sathnaga@linux.vnet.ibm.com, aneesh.kumar@linux.ibm.com,
sukadev@linux.vnet.ibm.com, bauerman@linux.ibm.com,
david@gibson.dropbear.id.au
Subject: [PATCH v2 2/2] KVM: PPC: Book3S HV: rework secure mem slot dropping
Date: Mon, 27 Jul 2020 12:24:29 -0700 [thread overview]
Message-ID: <1595877869-2746-3-git-send-email-linuxram@us.ibm.com> (raw)
In-Reply-To: <1595877869-2746-1-git-send-email-linuxram@us.ibm.com>
From: Laurent Dufour <ldufour@linux.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>
Reviewed-by: Bharata B Rao <bharata@linux.ibm.com>
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 | 52 +++++++++++++++++++++++++-------------
1 file changed, 35 insertions(+), 17 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 565f24b..0d49e34 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -594,35 +594,53 @@ 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;
+
+ mmap_read_lock(kvm->mm);
+
+ addr = slot->userspace_addr;
- 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)
--
1.8.3.1
next prev parent reply other threads:[~2020-07-27 19:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-27 19:24 [PATCH v2 0/2] Rework secure memslot dropping Ram Pai
2020-07-27 19:24 ` [PATCH v2 1/2] KVM: PPC: Book3S HV: move kvmppc_svm_page_out up Ram Pai
2020-07-27 19:24 ` Ram Pai [this message]
2020-07-28 5:52 ` [PATCH v2 0/2] Rework secure memslot dropping Paul Mackerras
-- strict thread matches above, loose matches on Subject: below --
2020-07-21 10:42 Laurent Dufour
2020-07-21 10:42 ` [PATCH v2 2/2] KVM: PPC: Book3S HV: rework secure mem slot dropping Laurent Dufour
2020-07-21 21:37 ` Ram Pai
2020-07-22 7:18 ` Laurent Dufour
2020-07-23 3:36 ` Bharata B Rao
2020-07-23 12:32 ` Laurent Dufour
2020-07-23 14:06 ` Laurent Dufour
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