linux-kernel - Re: [PATCH v3 07/13] KVM/nVMX: Use kvm_vcpu_map when mapping the virtual APIC page

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Message-ID: <1540109359.11839.30.camel@amazon.de>
Date:   Sun, 21 Oct 2018 08:09:19 +0000
From:   "Raslan, KarimAllah" <karahmed@...zon.de>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "rkrcmar@...hat.com" <rkrcmar@...hat.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>
Subject: Re: [PATCH v3 07/13] KVM/nVMX: Use kvm_vcpu_map when mapping the
 virtual APIC page

Sorry! please ignore this patch in favor of its RESEND. I realized that a few 
lines from it leaked into another patch series. The "RESEND" should have this 
fixed.

On Sun, 2018-10-21 at 00:22 +0200, 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.
> 
> Signed-off-by: KarimAllah Ahmed <karahmed@...zon.de>
> ---
> v1 -> v2:
> - Do not change the lifecycle of the mapping (pbonzini)
> - Use pfn_to_hpa instead of gfn_to_gpa
> ---
>  arch/x86/kvm/vmx.c | 34 +++++++++++-----------------------
>  1 file changed, 11 insertions(+), 23 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 5b15ca2..83a5e95 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -845,9 +845,8 @@ 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;
>  
>  	struct pi_desc *pi_desc;
> @@ -6152,11 +6151,12 @@ 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;
> @@ -8468,10 +8468,7 @@ static void free_nested(struct vcpu_vmx *vmx)
>  		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);
>  	if (vmx->nested.pi_desc_page) {
>  		kunmap(vmx->nested.pi_desc_page);
>  		kvm_release_page_dirty(vmx->nested.pi_desc_page);
> @@ -11394,6 +11391,7 @@ 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;
>  
> @@ -11426,11 +11424,7 @@ 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
> @@ -11445,11 +11439,8 @@ 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)) {
> @@ -13353,10 +13344,7 @@ static 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);
>  	if (vmx->nested.pi_desc_page) {
>  		kunmap(vmx->nested.pi_desc_page);
>  		kvm_release_page_dirty(vmx->nested.pi_desc_page);
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