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From: Sean Christopherson <sean.j.christopherson@intel.com>
To: "James Hogan" <jhogan@kernel.org>,
	"Paul Mackerras" <paulus@ozlabs.org>,
	"Christian Borntraeger" <borntraeger@de.ibm.com>,
	"Janosch Frank" <frankja@linux.ibm.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Marc Zyngier" <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
	Wanpeng Li <wanpengli@tencent.com>,
	kvm@vger.kernel.org, David Hildenbrand <david@redhat.com>,
	Joerg Roedel <joro@8bytes.org>, Cornelia Huck <cohuck@redhat.com>,
	linux-mips@vger.kernel.org,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	kvmarm@lists.cs.columbia.edu, Jim Mattson <jmattson@google.com>
Subject: [PATCH v3 13/15] KVM: Ensure validity of memslot with respect to kvm_get_dirty_log()
Date: Thu, 24 Oct 2019 16:07:42 -0700	[thread overview]
Message-ID: <20191024230744.14543-14-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20191024230744.14543-1-sean.j.christopherson@intel.com>

Rework kvm_get_dirty_log() so that it "returns" the associated memslot
on success.  A future patch will rework memslot handling such that
id_to_memslot() can return NULL, returning the memslot makes it more
obvious that the validity of the memslot has been verified, i.e.
precludes the need to add validity checks in the arch code that are
technically unnecessary.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/powerpc/kvm/book3s_pr.c |  6 +-----
 arch/s390/kvm/kvm-s390.c     | 12 ++----------
 include/linux/kvm_host.h     |  2 +-
 virt/kvm/kvm_main.c          | 27 +++++++++++++++++++--------
 4 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index 5368a5dbac22..f41a136d247f 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -1860,7 +1860,6 @@ static int kvmppc_vcpu_run_pr(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 static int kvm_vm_ioctl_get_dirty_log_pr(struct kvm *kvm,
 					 struct kvm_dirty_log *log)
 {
-	struct kvm_memslots *slots;
 	struct kvm_memory_slot *memslot;
 	struct kvm_vcpu *vcpu;
 	ulong ga, ga_end;
@@ -1870,15 +1869,12 @@ static int kvm_vm_ioctl_get_dirty_log_pr(struct kvm *kvm,
 
 	mutex_lock(&kvm->slots_lock);
 
-	r = kvm_get_dirty_log(kvm, log, &is_dirty);
+	r = kvm_get_dirty_log(kvm, log, &is_dirty, &memslot);
 	if (r)
 		goto out;
 
 	/* If nothing is dirty, don't bother messing with page tables. */
 	if (is_dirty) {
-		slots = kvm_memslots(kvm);
-		memslot = id_to_memslot(slots, log->slot);
-
 		ga = memslot->base_gfn << PAGE_SHIFT;
 		ga_end = ga + (memslot->npages << PAGE_SHIFT);
 
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index c0e9929bdb34..a66eb2b9bf71 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -613,9 +613,8 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 {
 	int r;
 	unsigned long n;
-	struct kvm_memslots *slots;
 	struct kvm_memory_slot *memslot;
-	int is_dirty = 0;
+	int is_dirty;
 
 	if (kvm_is_ucontrol(kvm))
 		return -EINVAL;
@@ -626,14 +625,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 	if (log->slot >= KVM_USER_MEM_SLOTS)
 		goto out;
 
-	slots = kvm_memslots(kvm);
-	memslot = id_to_memslot(slots, log->slot);
-	r = -ENOENT;
-	if (!memslot->dirty_bitmap)
-		goto out;
-
-	kvm_arch_sync_dirty_log(kvm, memslot);
-	r = kvm_get_dirty_log(kvm, log, &is_dirty);
+	r = kvm_get_dirty_log(kvm, log, &is_dirty, &memslot);
 	if (r)
 		goto out;
 
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index cd204b7d2513..a19807a4a5ad 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -809,7 +809,7 @@ void kvm_arch_dirty_log_tlb_flush(struct kvm *kvm,
 #else /* !CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
 int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log);
 int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log,
-		      int *is_dirty);
+		      int *is_dirty, struct kvm_memory_slot **memslot);
 #endif
 
 int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9da9c801a237..0192dccfcec1 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1136,31 +1136,42 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
 }
 
 #ifndef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
-int kvm_get_dirty_log(struct kvm *kvm,
-			struct kvm_dirty_log *log, int *is_dirty)
+/**
+ * kvm_get_dirty_log - get a snapshot of dirty pages
+ * @kvm:	pointer to kvm instance
+ * @log:	slot id and address to which we copy the log
+ * @is_dirty:	set to '1' if any dirty pages were found
+ * @memslot:	set to the associated memslot, always valid on success
+ */
+int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log,
+		      int *is_dirty, struct kvm_memory_slot **memslot)
 {
 	struct kvm_memslots *slots;
-	struct kvm_memory_slot *memslot;
 	int i, as_id, id;
 	unsigned long n;
 	unsigned long any = 0;
 
+	*memslot = NULL;
+	*is_dirty = 0;
+
 	as_id = log->slot >> 16;
 	id = (u16)log->slot;
 	if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
 		return -EINVAL;
 
 	slots = __kvm_memslots(kvm, as_id);
-	memslot = id_to_memslot(slots, id);
-	if (!memslot->dirty_bitmap)
+	*memslot = id_to_memslot(slots, id);
+	if (!(*memslot)->dirty_bitmap)
 		return -ENOENT;
 
-	n = kvm_dirty_bitmap_bytes(memslot);
+	kvm_arch_sync_dirty_log(kvm, *memslot);
+
+	n = kvm_dirty_bitmap_bytes(*memslot);
 
 	for (i = 0; !any && i < n/sizeof(long); ++i)
-		any = memslot->dirty_bitmap[i];
+		any = (*memslot)->dirty_bitmap[i];
 
-	if (copy_to_user(log->dirty_bitmap, memslot->dirty_bitmap, n))
+	if (copy_to_user(log->dirty_bitmap, (*memslot)->dirty_bitmap, n))
 		return -EFAULT;
 
 	if (any)
-- 
2.22.0

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  parent reply	other threads:[~2019-10-24 23:08 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-24 23:07 [PATCH v3 00/15] KVM: Dynamically size memslot arrays Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 01/15] KVM: Reinstall old memslots if arch preparation fails Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 02/15] KVM: Don't free new memslot if allocation of said memslot fails Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 03/15] KVM: PPC: Move memslot memory allocation into prepare_memory_region() Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 04/15] KVM: x86: Allocate memslot resources during prepare_memory_region() Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 05/15] KVM: Drop kvm_arch_create_memslot() Sean Christopherson
2019-12-16  8:04   ` Christian Borntraeger
2019-10-24 23:07 ` [PATCH v3 06/15] KVM: Explicitly free allocated-but-unused dirty bitmap Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 07/15] KVM: Refactor error handling for setting memory region Sean Christopherson
2019-12-05  9:49   ` Philippe Mathieu-Daudé
2019-10-24 23:07 ` [PATCH v3 08/15] KVM: Move setting of memslot into helper routine Sean Christopherson
2019-12-05  9:54   ` Philippe Mathieu-Daudé
2019-10-24 23:07 ` [PATCH v3 09/15] KVM: Move memslot deletion to helper function Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 10/15] KVM: Simplify kvm_free_memslot() and all its descendents Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 11/15] KVM: Clean up local variable usage in __kvm_set_memory_region() Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 12/15] KVM: Provide common implementation for generic dirty log functions Sean Christopherson
2019-10-24 23:07 ` Sean Christopherson [this message]
2019-10-24 23:07 ` [PATCH v3 14/15] KVM: Terminate memslot walks via used_slots Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 15/15] KVM: Dynamically size memslot array based on number of used slots Sean Christopherson
2019-10-25 13:28 ` [PATCH v3 00/15] KVM: Dynamically size memslot arrays Christoffer Dall
2019-10-25 16:30 ` Marc Zyngier
2019-12-03 22:14 ` Sean Christopherson
2019-12-13 20:01   ` Sean Christopherson
2019-12-16  8:25     ` Christian Borntraeger
2019-12-17 17:55       ` Sean Christopherson

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