From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
Reiji Watanabe <reijiw@google.com>,
Ricardo Koller <ricarkol@google.com>,
David Matlack <dmatlack@google.com>,
Quentin Perret <qperret@google.com>,
Ben Gardon <bgardon@google.com>, Gavin Shan <gshan@redhat.com>,
Peter Xu <peterx@redhat.com>, Will Deacon <will@kernel.org>,
Sean Christopherson <seanjc@google.com>,
kvmarm@lists.linux.dev, Oliver Upton <oliver.upton@linux.dev>
Subject: [PATCH v2 09/15] KVM: arm64: Free removed stage-2 tables in RCU callback
Date: Fri, 7 Oct 2022 23:28:12 +0000 [thread overview]
Message-ID: <20221007232818.459650-10-oliver.upton@linux.dev> (raw)
In-Reply-To: <20221007232818.459650-1-oliver.upton@linux.dev>
There is no real urgency to free a stage-2 subtree that was pruned.
Nonetheless, KVM does the tear down in the stage-2 fault path while
holding the MMU lock.
Free removed stage-2 subtrees after an RCU grace period. To guarantee
all stage-2 table pages are freed before killing a VM, add an
rcu_barrier() to the flush path.
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
arch/arm64/kvm/mmu.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 04a25319abb0..66eede0fbb36 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -104,9 +104,21 @@ static void *kvm_host_zalloc_pages_exact(size_t size)
static struct kvm_pgtable_mm_ops kvm_s2_mm_ops;
+static void stage2_free_removed_table_rcu_cb(struct rcu_head *head)
+{
+ struct page *page = container_of(head, struct page, rcu_head);
+ void *pgtable = page_to_virt(page);
+ u32 level = page_private(page);
+
+ kvm_pgtable_stage2_free_removed(&kvm_s2_mm_ops, pgtable, level);
+}
+
static void stage2_free_removed_table(void *addr, u32 level)
{
- kvm_pgtable_stage2_free_removed(&kvm_s2_mm_ops, addr, level);
+ struct page *page = virt_to_page(addr);
+
+ set_page_private(page, (unsigned long)level);
+ call_rcu(&page->rcu_head, stage2_free_removed_table_rcu_cb);
}
static void kvm_host_get_page(void *addr)
--
2.38.0.rc1.362.ged0d419d3c-goog
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next prev parent reply other threads:[~2022-10-07 23:32 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-07 23:28 [PATCH v2 00/15] KVM: arm64: Parallel stage-2 fault handling Oliver Upton
2022-10-07 23:28 ` [PATCH v2 01/15] KVM: arm64: Combine visitor arguments into a context structure Oliver Upton
2022-10-07 23:28 ` [PATCH v2 02/15] KVM: arm64: Stash observed pte value in visitor context Oliver Upton
2022-10-07 23:28 ` [PATCH v2 03/15] KVM: arm64: Pass mm_ops through the " Oliver Upton
2022-10-07 23:28 ` [PATCH v2 04/15] KVM: arm64: Don't pass kvm_pgtable through kvm_pgtable_walk_data Oliver Upton
2022-10-07 23:28 ` [PATCH v2 05/15] KVM: arm64: Add a helper to tear down unlinked stage-2 subtrees Oliver Upton
2022-10-07 23:28 ` [PATCH v2 06/15] KVM: arm64: Tear down unlinked stage-2 subtree after break-before-make Oliver Upton
2022-10-28 18:41 ` Ricardo Koller
2022-10-28 18:43 ` Ricardo Koller
2022-10-28 18:53 ` Ricardo Koller
2022-10-07 23:28 ` [PATCH v2 07/15] KVM: arm64: Use an opaque type for pteps Oliver Upton
2022-10-19 23:17 ` Sean Christopherson
2022-10-20 8:32 ` Oliver Upton
2022-10-27 22:31 ` Oliver Upton
2022-10-07 23:28 ` [PATCH v2 08/15] KVM: arm64: Protect stage-2 traversal with RCU Oliver Upton
2022-10-19 23:29 ` Sean Christopherson
2022-10-20 8:34 ` Oliver Upton
2022-10-07 23:28 ` Oliver Upton [this message]
2022-10-07 23:28 ` [PATCH v2 10/15] KVM: arm64: Atomically update stage 2 leaf attributes in parallel walks Oliver Upton
2022-10-07 23:30 ` [PATCH v2 11/15] KVM: arm64: Split init and set for table PTE Oliver Upton
2022-10-07 23:31 ` [PATCH v2 12/15] KVM: arm64: Make block->table PTE changes parallel-aware Oliver Upton
2022-10-07 23:32 ` [PATCH v2 13/15] KVM: arm64: Make leaf->leaf " Oliver Upton
2022-10-07 23:32 ` [PATCH v2 14/15] KVM: arm64: Make table->block " Oliver Upton
2022-10-07 23:32 ` [PATCH v2 15/15] KVM: arm64: Handle stage-2 faults in parallel Oliver Upton
[not found] ` <202210081008.A9PLyQx2-lkp@intel.com>
2022-10-08 3:14 ` Oliver Upton
2022-10-19 23:32 ` Sean Christopherson
2022-10-20 8:35 ` Oliver Upton
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