Re: [PATCH 07/10] KVM/nVMX: Use kvm_vcpu_map when mapping the posted interrupt descriptor table

Paolo Bonzini
2018-04-12T14:39:23Z

On 21/02/2018 18:47, KarimAllah Ahmed wrote:
> ... since using kvm_vcpu_gpa_to_page() and kmap() will only work for guest
> memory that has a "struct page".
>
> The life-cycle of the mapping also changes to avoid doing map and unmap on
> every single exit (which becomes very expesive once we use memremap). Now
> the memory is mapped and only unmapped when a new VMCS12 is loaded into the
> vCPU (or when the vCPU is freed!).
>
> Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>

Same here, let's change the lifecycle separately.

Paolo

> ---
> arch/x86/kvm/vmx.c | 45 +++++++++++++--------------------------------
> 1 file changed, 13 insertions(+), 32 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index a700338..7b29419 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -461,7 +461,7 @@ struct nested_vmx {
> */
> struct page *apic_access_page;
> struct kvm_host_map virtual_apic_map;
> - struct page *pi_desc_page;
> + struct kvm_host_map pi_desc_map;
> struct kvm_host_map msr_bitmap_map;
>
> struct pi_desc *pi_desc;
> @@ -7666,6 +7666,7 @@ static inline void nested_release_vmcs12(struct vcpu_vmx *vmx)
> vmx->nested.cached_vmcs12, 0, VMCS12_SIZE);
>
> kvm_vcpu_unmap(&vmx->nested.virtual_apic_map);
> + kvm_vcpu_unmap(&vmx->nested.pi_desc_map);
> kvm_vcpu_unmap(&vmx->nested.msr_bitmap_map);
>
> vmx->nested.current_vmptr = -1ull;
> @@ -7698,14 +7699,9 @@ static void free_nested(struct vcpu_vmx *vmx)
> vmx->nested.apic_access_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);
> - vmx->nested.pi_desc_page = NULL;
> - vmx->nested.pi_desc = NULL;
> - }
> -
> + kvm_vcpu_unmap(&vmx->nested.pi_desc_map);
> kvm_vcpu_unmap(&vmx->nested.msr_bitmap_map);
> + vmx->nested.pi_desc = NULL;
>
> free_loaded_vmcs(&vmx->nested.vmcs02);
> }
> @@ -10278,24 +10274,16 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu,
> }
>
> if (nested_cpu_has_posted_intr(vmcs12)) {
> - if (vmx->nested.pi_desc_page) { /* shouldn't happen */
> - kunmap(vmx->nested.pi_desc_page);
> - kvm_release_page_dirty(vmx->nested.pi_desc_page);
> - vmx->nested.pi_desc_page = NULL;
> + map = &vmx->nested.pi_desc_map;
> +
> + if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->posted_intr_desc_addr), map)) {
> + vmx->nested.pi_desc =
> + (struct pi_desc *)(((void *)map->kaddr) +
> + offset_in_page(vmcs12->posted_intr_desc_addr));
> + vmcs_write64(POSTED_INTR_DESC_ADDR, pfn_to_hpa(map->pfn) +
> + offset_in_page(vmcs12->posted_intr_desc_addr));
> }
> - page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->posted_intr_desc_addr);
> - if (is_error_page(page))
> - return;
> - vmx->nested.pi_desc_page = page;
> - vmx->nested.pi_desc = kmap(vmx->nested.pi_desc_page);
> - vmx->nested.pi_desc =
> - (struct pi_desc *)((void *)vmx->nested.pi_desc +
> - (unsigned long)(vmcs12->posted_intr_desc_addr &
> - (PAGE_SIZE - 1)));
> - vmcs_write64(POSTED_INTR_DESC_ADDR,
> - page_to_phys(vmx->nested.pi_desc_page) +
> - (unsigned long)(vmcs12->posted_intr_desc_addr &
> - (PAGE_SIZE - 1)));
> +
> }
> if (nested_vmx_prepare_msr_bitmap(vcpu, vmcs12))
> vmcs_set_bits(CPU_BASED_VM_EXEC_CONTROL,
> @@ -11893,13 +11881,6 @@ 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.pi_desc_page) {
> - kunmap(vmx->nested.pi_desc_page);
> - kvm_release_page_dirty(vmx->nested.pi_desc_page);
> - vmx->nested.pi_desc_page = NULL;
> - vmx->nested.pi_desc = NULL;
> - }
> -
> /*
> * We are now running in L2, mmu_notifier will force to reload the
> * page's hpa for L2 vmcs. Need to reload it for L1 before entering L1.
>