From: linmiaohe <linmiaohe@huawei.com>
To: <pbonzini@redhat.com>, <rkrcmar@redhat.com>,
<sean.j.christopherson@intel.com>, <vkuznets@redhat.com>,
<wanpengli@tencent.com>, <jmattson@google.com>, <joro@8bytes.org>,
<tglx@linutronix.de>, <mingo@redhat.com>, <bp@alien8.de>,
<hpa@zytor.com>
Cc: <linmiaohe@huawei.com>, <kvm@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <x86@kernel.org>
Subject: [PATCH] KVM: x86: avoid some unnecessary copy in __x86_set_memory_region()
Date: Thu, 23 Jan 2020 11:00:13 +0800 [thread overview]
Message-ID: <1579748413-432-1-git-send-email-linmiaohe@huawei.com> (raw)
From: Miaohe Lin <linmiaohe@huawei.com>
Only userspace_addr and npages are passed to vm_munmap() when remove a
memory region. So we shouldn't copy the integral kvm_memory_slot struct.
No functional change intended.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
arch/x86/kvm/x86.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d1faa74981d9..767f29877938 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9735,9 +9735,9 @@ void kvm_arch_sync_events(struct kvm *kvm)
int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size)
{
int i, r;
- unsigned long hva;
+ unsigned long hva, uaddr, npages;
struct kvm_memslots *slots = kvm_memslots(kvm);
- struct kvm_memory_slot *slot, old;
+ struct kvm_memory_slot *slot;
/* Called with kvm->slots_lock held. */
if (WARN_ON(id >= KVM_MEM_SLOTS_NUM))
@@ -9761,9 +9761,10 @@ int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size)
return 0;
hva = 0;
+ uaddr = slot->userspace_addr;
+ npages = slot->npages;
}
- old = *slot;
for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
struct kvm_userspace_memory_region m;
@@ -9778,7 +9779,7 @@ int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size)
}
if (!size)
- vm_munmap(old.userspace_addr, old.npages * PAGE_SIZE);
+ vm_munmap(uaddr, npages * PAGE_SIZE);
return 0;
}
--
2.19.1
next reply other threads:[~2020-01-23 2:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-23 3:00 linmiaohe [this message]
2020-01-23 12:15 ` [PATCH] KVM: x86: avoid some unnecessary copy in __x86_set_memory_region() Paolo Bonzini
2020-01-26 0:39 ` kbuild test robot
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