On Wed, Jan 09, 2019 at 10:42:07AM +0100, KarimAllah Ahmed wrote:
> Use kvm_vcpu_map when mapping the virtual APIC page since using
> kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory that has
> a "struct page".
> 
> One additional semantic change is that the virtual host mapping lifecycle
> has changed a bit. It now has the same lifetime of the pinning of the
> virtual APIC page on the host side.

Could you expand a bit on the 'same lifetime .. on the host side'  to be
obvious for folks what exactly the semantic is?

And how does this ring with this comment:
> 
> Signed-off-by: KarimAllah Ahmed <[email protected]>
> ---
> v4 -> v5:
> - unmap with dirty flag
> 
> v1 -> v2:
> - Do not change the lifecycle of the mapping (pbonzini)

.. Where Paolo does not want the semantics of the mapping to be changed?

Code wise feel free to smack my Reviewed-by on it, but obviously the
question on the above comment needs to be resolved.

Thank you.

> - Use pfn_to_hpa instead of gfn_to_gpa
> ---
>  arch/x86/kvm/vmx/nested.c | 32 +++++++++++---------------------
>  arch/x86/kvm/vmx/vmx.c    |  5 ++---
>  arch/x86/kvm/vmx/vmx.h    |  2 +-
>  3 files changed, 14 insertions(+), 25 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 4127ad9..dcff99d 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -229,10 +229,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
>               kvm_release_page_dirty(vmx->nested.apic_access_page);
>               vmx->nested.apic_access_page = NULL;
>       }
> -     if (vmx->nested.virtual_apic_page) {
> -             kvm_release_page_dirty(vmx->nested.virtual_apic_page);
> -             vmx->nested.virtual_apic_page = NULL;
> -     }
> +     kvm_vcpu_unmap(&vmx->nested.virtual_apic_map, true);
>       if (vmx->nested.pi_desc_page) {
>               kunmap(vmx->nested.pi_desc_page);
>               kvm_release_page_dirty(vmx->nested.pi_desc_page);
> @@ -2817,6 +2814,7 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu 
> *vcpu)
>  {
>       struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
>       struct vcpu_vmx *vmx = to_vmx(vcpu);
> +     struct kvm_host_map *map;
>       struct page *page;
>       u64 hpa;
>  
> @@ -2849,11 +2847,7 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu 
> *vcpu)
>       }
>  
>       if (nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW)) {
> -             if (vmx->nested.virtual_apic_page) { /* shouldn't happen */
> -                     kvm_release_page_dirty(vmx->nested.virtual_apic_page);
> -                     vmx->nested.virtual_apic_page = NULL;
> -             }
> -             page = kvm_vcpu_gpa_to_page(vcpu, 
> vmcs12->virtual_apic_page_addr);
> +             map = &vmx->nested.virtual_apic_map;
>  
>               /*
>                * If translation failed, VM entry will fail because
> @@ -2868,11 +2862,9 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu 
> *vcpu)
>                * control.  But such a configuration is useless, so
>                * let's keep the code simple.
>                */
> -             if (!is_error_page(page)) {
> -                     vmx->nested.virtual_apic_page = page;
> -                     hpa = page_to_phys(vmx->nested.virtual_apic_page);
> -                     vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, hpa);
> -             }
> +             if (!kvm_vcpu_map(vcpu, 
> gpa_to_gfn(vmcs12->virtual_apic_page_addr), map))
> +                     vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, 
> pfn_to_hpa(map->pfn));
> +
>       }
>  
>       if (nested_cpu_has_posted_intr(vmcs12)) {
> @@ -3279,11 +3271,12 @@ static void 
> vmx_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu)
>  
>       max_irr = find_last_bit((unsigned long *)vmx->nested.pi_desc->pir, 256);
>       if (max_irr != 256) {
> -             vapic_page = kmap(vmx->nested.virtual_apic_page);
> +             vapic_page = vmx->nested.virtual_apic_map.hva;
> +             if (!vapic_page)
> +                     return;
> +
>               __kvm_apic_update_irr(vmx->nested.pi_desc->pir,
>                       vapic_page, &max_irr);
> -             kunmap(vmx->nested.virtual_apic_page);
> -
>               status = vmcs_read16(GUEST_INTR_STATUS);
>               if ((u8)max_irr > ((u8)status & 0xff)) {
>                       status &= ~0xff;
> @@ -3917,10 +3910,7 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 
> exit_reason,
>               kvm_release_page_dirty(vmx->nested.apic_access_page);
>               vmx->nested.apic_access_page = NULL;
>       }
> -     if (vmx->nested.virtual_apic_page) {
> -             kvm_release_page_dirty(vmx->nested.virtual_apic_page);
> -             vmx->nested.virtual_apic_page = NULL;
> -     }
> +     kvm_vcpu_unmap(&vmx->nested.virtual_apic_map, true);
>       if (vmx->nested.pi_desc_page) {
>               kunmap(vmx->nested.pi_desc_page);
>               kvm_release_page_dirty(vmx->nested.pi_desc_page);
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 71d88df..e13308e 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -3627,14 +3627,13 @@ static bool vmx_guest_apic_has_interrupt(struct 
> kvm_vcpu *vcpu)
>  
>       if (WARN_ON_ONCE(!is_guest_mode(vcpu)) ||
>               !nested_cpu_has_vid(get_vmcs12(vcpu)) ||
> -             WARN_ON_ONCE(!vmx->nested.virtual_apic_page))
> +             WARN_ON_ONCE(!vmx->nested.virtual_apic_map.gfn))
>               return false;
>  
>       rvi = vmx_get_rvi();
>  
> -     vapic_page = kmap(vmx->nested.virtual_apic_page);
> +     vapic_page = vmx->nested.virtual_apic_map.hva;
>       vppr = *((u32 *)(vapic_page + APIC_PROCPRI));
> -     kunmap(vmx->nested.virtual_apic_page);
>  
>       return ((rvi & 0xf0) > (vppr & 0xf0));
>  }
> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
> index 6fb69d8..f618f52 100644
> --- a/arch/x86/kvm/vmx/vmx.h
> +++ b/arch/x86/kvm/vmx/vmx.h
> @@ -142,7 +142,7 @@ struct nested_vmx {
>        * pointers, so we must keep them pinned while L2 runs.
>        */
>       struct page *apic_access_page;
> -     struct page *virtual_apic_page;
> +     struct kvm_host_map virtual_apic_map;
>       struct page *pi_desc_page;
>  
>       struct kvm_host_map msr_bitmap_map;
> -- 
> 2.7.4
> 

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