Re: [PATCH v7 053/102] KVM: TDX: don't request KVM_REQ_APIC_PAGE_RELOAD

Isaku Yamahata
2022-07-19T18:13:04Z

On Tue, Jul 12, 2022 at 02:14:45PM +0800,
Chao Gao <chao.gao@intel.com> wrote:

> On Tue, Jul 12, 2022 at 11:47:43AM +0800, Yuan Yao wrote:
> >On Mon, Jun 27, 2022 at 02:53:45PM -0700, isaku.yamahata@intel.com wrote:
> >> From: Isaku Yamahata <isaku.yamahata@intel.com>
> >>
> >> TDX doesn't need APIC page depending on vapic and its callback is
> >> WARN_ON_ONCE(is_tdx). To avoid unnecessary overhead and WARN_ON_ONCE(),
> >> skip requesting KVM_REQ_APIC_PAGE_RELOAD when TD.
>
> !kvm_gfn_shared_mask() doesn't ensure the VM is a TD. Right?

That's right. I changed the check as follows.

commit 6753fc53f3b3fcbbd07ac688578ff5fb7f7f7d96 (HEAD)
Author: Isaku Yamahata <isaku.yamahata@intel.com>
Date: Wed Mar 30 22:32:03 2022 -0700

KVM: TDX: don't request KVM_REQ_APIC_PAGE_RELOAD

TDX doesn't need APIC page depending on vapic and its callback is
WARN_ON_ONCE(is_tdx). To avoid unnecessary overhead and WARN_ON_ONCE(),
skip requesting KVM_REQ_APIC_PAGE_RELOAD when TD.

WARNING: arch/x86/kvm/vmx/main.c:696 vt_set_apic_access_page_addr+0x3c/0x50 [kvm_intel]
RIP: 0010:vt_set_apic_access_page_addr+0x3c/0x50 [kvm_intel]
Call Trace:
vcpu_enter_guest+0x145d/0x24d0 [kvm]
kvm_arch_vcpu_ioctl_run+0x25d/0xcc0 [kvm]
kvm_vcpu_ioctl+0x414/0xa30 [kvm]
__x64_sys_ioctl+0xc0/0x100
do_syscall_64+0x39/0xc0
entry_SYSCALL_64_after_hwframe+0x44/0xae

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 51ba2d163ec4..bfd7ed6ba385 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10045,7 +10045,9 @@ void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm,
* Update it when it becomes invalid.
*/
apic_address = gfn_to_hva(kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT);
- if (start <= apic_address && apic_address < end)
+ /* TDX doesn't need APIC page. */
+ if (kvm->arch.vm_type != KVM_X86_TDX_VM &&
+ start <= apic_address && apic_address < end)
kvm_make_all_cpus_request(kvm, KVM_REQ_APIC_PAGE_RELOAD);
}

--
Isaku Yamahata <isaku.yamahata@gmail.com>