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Message-ID: <20190123175711.GL19289@Konrads-MacBook-Pro.local>
Date: Wed, 23 Jan 2019 12:57:33 -0500
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: KarimAllah Ahmed <karahmed@...zon.de>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
pbonzini@...hat.com, rkrcmar@...hat.com
Subject: Re: [PATCH v5 07/13] KVM/nVMX: Use kvm_vcpu_map when mapping the
virtual APIC page
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 <karahmed@...zon.de>
> ---
> 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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