linux-kernel - [RFC PATCH 03/18] KVM: Put struct kvm pointer in memslot

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Message-ID: <20240710234222.2333120-4-jthoughton@google.com>
Date: Wed, 10 Jul 2024 23:42:07 +0000
From: James Houghton <jthoughton@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	James Morse <james.morse@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
	Zenghui Yu <yuzenghui@...wei.com>, Sean Christopherson <seanjc@...gle.com>, Shuah Khan <shuah@...nel.org>, 
	Peter Xu <peterx@...hat.org>, Axel Rasmussen <axelrasmussen@...gle.com>, 
	David Matlack <dmatlack@...gle.com>, James Houghton <jthoughton@...gle.com>, kvm@...r.kernel.org, 
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev
Subject: [RFC PATCH 03/18] KVM: Put struct kvm pointer in memslot

Because a gfn having userfault enabled is tied to a struct kvm, we need
a pointer to it. We could pass the kvm pointer around in the routines we
need it, but that is a lot of churn, and there isn't much of a downside
to simply storing the pointer in the memslot.

Signed-off-by: James Houghton <jthoughton@...gle.com>
---
 include/linux/kvm_host.h | 2 ++
 virt/kvm/kvm_main.c      | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index f0d4db2d64af..c1eb59a3141b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -596,6 +596,8 @@ struct kvm_memory_slot {
 		pgoff_t pgoff;
 	} gmem;
 #endif
+
+	struct kvm *kvm;
 };
 
 static inline bool kvm_slot_can_be_private(const struct kvm_memory_slot *slot)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index fb7972e61439..ffa452a13672 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1769,6 +1769,7 @@ static void kvm_copy_memslot(struct kvm_memory_slot *dest,
 	dest->flags = src->flags;
 	dest->id = src->id;
 	dest->as_id = src->as_id;
+	dest->kvm = src->kvm;
 }
 
 static void kvm_invalidate_memslot(struct kvm *kvm,
@@ -2078,6 +2079,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	new->npages = npages;
 	new->flags = mem->flags;
 	new->userspace_addr = mem->userspace_addr;
+	new->kvm = kvm;
 	if (mem->flags & KVM_MEM_GUEST_MEMFD) {
 		r = kvm_gmem_bind(kvm, new, mem->guest_memfd, mem->guest_memfd_offset);
 		if (r)
-- 
2.45.2.993.g49e7a77208-goog