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Date: Thu, 21 Aug 2014 16:08:33 +0800
From: Wanpeng Li <wanpeng.li@...ux.intel.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: Marcelo Tosatti <mtosatti@...hat.com>,
Gleb Natapov <gleb@...nel.org>,
Zhang Yang <yang.z.zhang@...el.com>, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/2] KVM: nVMX: introduce
apic_access_and_virtual_page_valid
Hi Paolo,
On Wed, Aug 20, 2014 at 12:50:38PM +0200, Paolo Bonzini wrote:
>Il 20/08/2014 11:45, Wanpeng Li ha scritto:
>> Introduce apic_access_and_virtual_page_valid() to check the valid
>> of nested apic access page and virtual apic page earlier.
>>
>> Signed-off-by: Wanpeng Li <wanpeng.li@...ux.intel.com>
>> ---
>> arch/x86/kvm/vmx.c | 82 ++++++++++++++++++++++++++++++------------------------
>> 1 file changed, 46 insertions(+), 36 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index caf239d..02bc07d 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -7838,6 +7838,50 @@ static void vmx_inject_page_fault_nested(struct kvm_vcpu *vcpu,
>> kvm_inject_page_fault(vcpu, fault);
>> }
>>
>> +static bool apic_access_and_virtual_page_valid(struct kvm_vcpu *vcpu,
>> + struct vmcs12 *vmcs12)
>> +{
>> + struct vcpu_vmx *vmx = to_vmx(vcpu);
>> +
>> + if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {
>> + if (!PAGE_ALIGNED(vmcs12->apic_access_addr))
>> + /*TODO: Also verify bits beyond physical address width are 0*/
>> + return false;
>> +
>> + /*
>> + * Translate L1 physical address to host physical
>> + * address for vmcs02. Keep the page pinned, so this
>> + * physical address remains valid. We keep a reference
>> + * to it so we can release it later.
>> + */
>> + if (vmx->nested.apic_access_page) /* shouldn't happen */
>> + nested_release_page(vmx->nested.apic_access_page);
>> + vmx->nested.apic_access_page =
>> + nested_get_page(vcpu, vmcs12->apic_access_addr);
>> + }
>> +
>> + if (nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW)) {
>> + if (vmx->nested.virtual_apic_page) /* shouldn't happen */
>> + nested_release_page(vmx->nested.virtual_apic_page);
>> + vmx->nested.virtual_apic_page =
>> + nested_get_page(vcpu, vmcs12->virtual_apic_page_addr);
>> +
>> + /*
>> + * Failing the vm entry is _not_ what the processor does
>> + * but it's basically the only possibility we have.
>> + * We could still enter the guest if CR8 load exits are
>> + * enabled, CR8 store exits are enabled, and virtualize APIC
>> + * access is disabled; in this case the processor would never
>> + * use the TPR shadow and we could simply clear the bit from
>> + * the execution control. But such a configuration is useless,
>> + * so let's keep the code simple.
>> + */
>> + if (!vmx->nested.virtual_apic_page)
>> + return false;
>> + }
>> + return true;
>> +}
>> +
>> static void vmx_start_preemption_timer(struct kvm_vcpu *vcpu)
>> {
>> u64 preemption_timeout = get_vmcs12(vcpu)->vmx_preemption_timer_value;
>> @@ -7984,16 +8028,6 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
>>
>> if (exec_control & SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES) {
>> /*
>> - * Translate L1 physical address to host physical
>> - * address for vmcs02. Keep the page pinned, so this
>> - * physical address remains valid. We keep a reference
>> - * to it so we can release it later.
>> - */
>> - if (vmx->nested.apic_access_page) /* shouldn't happen */
>> - nested_release_page(vmx->nested.apic_access_page);
>> - vmx->nested.apic_access_page =
>> - nested_get_page(vcpu, vmcs12->apic_access_addr);
>> - /*
>> * If translation failed, no matter: This feature asks
>> * to exit when accessing the given address, and if it
>> * can never be accessed, this feature won't do
>> @@ -8040,30 +8074,8 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
>> exec_control |= vmcs12->cpu_based_vm_exec_control;
>>
>> if (exec_control & CPU_BASED_TPR_SHADOW) {
>> - if (vmx->nested.virtual_apic_page)
>> - nested_release_page(vmx->nested.virtual_apic_page);
>> - vmx->nested.virtual_apic_page =
>> - nested_get_page(vcpu, vmcs12->virtual_apic_page_addr);
>> - if (!vmx->nested.virtual_apic_page)
>> - exec_control &=
>> - ~CPU_BASED_TPR_SHADOW;
>> - else
>> - vmcs_write64(VIRTUAL_APIC_PAGE_ADDR,
>> + vmcs_write64(VIRTUAL_APIC_PAGE_ADDR,
>> page_to_phys(vmx->nested.virtual_apic_page));
>> -
>> - /*
>> - * Failing the vm entry is _not_ what the processor does
>> - * but it's basically the only possibility we have.
>> - * We could still enter the guest if CR8 load exits are
>> - * enabled, CR8 store exits are enabled, and virtualize APIC
>> - * access is disabled; in this case the processor would never
>> - * use the TPR shadow and we could simply clear the bit from
>> - * the execution control. But such a configuration is useless,
>> - * so let's keep the code simple.
>> - */
>> - if (!vmx->nested.virtual_apic_page)
>> - nested_vmx_failValid(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD);
>> -
>> vmcs_write32(TPR_THRESHOLD, vmcs12->tpr_threshold);
>> } else if (vm_need_tpr_shadow(vmx->vcpu.kvm))
>> vmcs_write64(VIRTUAL_APIC_PAGE_ADDR,
>> @@ -8230,9 +8242,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
>> return 1;
>> }
>>
>> - if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES) &&
>> - !PAGE_ALIGNED(vmcs12->apic_access_addr)) {
>> - /*TODO: Also verify bits beyond physical address width are 0*/
>> + if (!apic_access_and_virtual_page_valid(vcpu, vmcs12)) {
>> nested_vmx_failValid(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD);
>> return 1;
>> }
>>
>
>Thanks Wanpeng. The code now looks good. Just one thing: please swap
>them, so that the series remains bisectable.
>
Do you mean the first patch introduce nested_get_vmcs12_pages() and the
second patch implement nested TPR shadow/threshold emulation?
>Also, I think nested_get_vmcs12_pages would be a better name for the
>function. apic_access_and_virtual_page_valid doesn't hint at the side
>effects of the function (for example calling nested_get_page).
>
Will do.
Regards,
Wanpeng Li
>The way I swap patches is by using "git checkout -p" like this:
>
> git branch tpr-shadow-old
> git reset --hard HEAD^^
> git checkout -p tpr-shadow-old
> ... pick hunks related to the second patch ...
> git commit -c tpr-shadow-old
> ... edit commit message if needed ...
> git checkout -p tpr-shadow-old
> ... pick hunks related to the first patch ...
> git commit -C tpr-shadow-old^
> ... edit commit message if needed ...
> git diff tpr-shadow-old HEAD
>
>Paolo
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