On 07/15/2014 08:40 PM, Gleb Natapov wrote:
On Tue, Jul 15, 2014 at 08:28:22PM +0800, Tang Chen wrote:
On 07/15/2014 08:09 PM, Gleb Natapov wrote:
On Tue, Jul 15, 2014 at 01:52:40PM +0200, Jan Kiszka wrote:
......
I cannot follow your concerns yet. Specifically, how should
APIC_ACCESS_ADDR (the VMCS field, right?) change while L2 is running? We
currently pin/unpin on L1->L2/L2->L1, respectively. Or what do you mean?
I am talking about this case:
if (cpu_has_secondary_exec_ctrls()) {a
} else {
exec_control |=
SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
vmcs_write64(APIC_ACCESS_ADDR,
page_to_phys(vcpu->kvm->arch.apic_access_page));
}
We do not pin here.
Hi Gleb,
7905 if (exec_control&
SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES) {
......
7912 if (vmx->nested.apic_access_page) /* shouldn't
happen */
7913 nested_release_page(vmx->nested.apic_access_page);
7914 vmx->nested.apic_access_page =
7915 nested_get_page(vcpu,
vmcs12->apic_access_addr);
I thought you were talking about the problem here. We pin
vmcs12->apic_access_addr
in memory. And I think we should do the same thing to this page as to L1 vm.
Right ?
Nested kvm pins a lot of pages, it will probably be not easy to handle all of
them,
so for now I am concerned with non nested case only (but nested should continue
to
work obviously, just pin pages like it does now).
True. I will work on it.
And also, when using PCI passthrough, kvm_pin_pages() also pins some
pages. This is
also in my todo list.
But sorry, a little strange. I didn't find where
vmcs12->apic_access_addr is allocated
or initialized... Would you please tell me ?
......
7922 if (!vmx->nested.apic_access_page)
7923 exec_control&=
7924 ~SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
7925 else
7926 vmcs_write64(APIC_ACCESS_ADDR,
7927 page_to_phys(vmx->nested.apic_access_page));
7928 } else if
(vm_need_virtualize_apic_accesses(vmx->vcpu.kvm)) {
7929 exec_control |=
7930 SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
7931 vmcs_write64(APIC_ACCESS_ADDR,
7932 page_to_phys(vcpu->kvm->arch.apic_access_page));
7933 }
And yes, we have the problem you said here. We can migrate the page while L2
vm is running.
So I think we should enforce L2 vm to exit to L1. Right ?
We can request APIC_ACCESS_ADDR reload during L2->L1 vmexit emulation, so
if APIC_ACCESS_ADDR changes while L2 is running it will be reloaded for L1 too.
apic pages for L2 and L1 are not the same page, right ?
I think, just like we are doing in patch 5/5, we cannot wait for the
next L2->L1 vmexit.
We should enforce a L2->L1 vmexit in mmu_notifier, just like
make_all_cpus_request() does.
Am I right ?
Thanks.
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