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[Qemu-devel] Re: [PATCH] kvm: Fix overlapping check for memory slots
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] Re: [PATCH] kvm: Fix overlapping check for memory slots |
Date: |
Mon, 13 Apr 2009 10:50:40 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
Sheng Yang wrote:
> On Saturday 11 April 2009 17:48:04 Jan Kiszka wrote:
>> This nice little buglet complicates a smarter slot management in qemu
>> user space just "slightly". Sigh...
>>
>> -------->
>>
>> When checking for overlapping slots on registration of a new one, kvm
>> currently also considers zero-length (ie. deleted) slots and rejects
>> requests incorrectly. This finally denies user space from joining slots.
>> Fix the check by skipping deleted slots.
>>
>> Signed-off-by: Jan Kiszka <address@hidden>
>> ---
>>
>> virt/kvm/kvm_main.c | 2 +-
>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
>> index 363af32..18f06d2 100644
>> --- a/virt/kvm/kvm_main.c
>> +++ b/virt/kvm/kvm_main.c
>> @@ -1117,7 +1117,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
>> for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
>> struct kvm_memory_slot *s = &kvm->memslots[i];
>>
>> - if (s == memslot)
>> + if (s == memslot || !s->npages)
>> continue;
>> if (!((base_gfn + npages <= s->base_gfn) ||
>> (base_gfn >= s->base_gfn + s->npages)))
>
> Is it necessary to preserve a valid base_gfn/flags/etc for a zeroed slot?
> Seems kvm_free_physmem_slot didn't clean them.
It is not necessary as long as we ignore such slots (as this patch does).
Jan
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