Re: [PATCH v2 4/5] kvm: Remove ept_identity_pagetable from struct kvm_arch.

Tang Chen
2014-07-09T02:06:41Z

On 07/08/2014 09:01 PM, Tang Chen wrote:
> kvm_arch->ept_identity_pagetable holds the ept identity pagetable page. But
> it is never used to refer to the page at all.
>
> In vcpu initialization, it indicates two things:
> 1. indicates if ept page is allocated
> 2. indicates if a memory slot for identity page is initialized
>
> Actually, kvm_arch->ept_identity_pagetable_done is enough to tell if the ept
> identity pagetable is initialized. So we can remove ept_identity_pagetable.
>
> Signed-off-by: Tang Chen<tangchen@cn.fujitsu.com>
> ---
> arch/x86/include/asm/kvm_host.h | 1 -
> arch/x86/kvm/vmx.c | 25 +++++++++++--------------
> 2 files changed, 11 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 4931415..62f973e 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -578,7 +578,6 @@ struct kvm_arch {
>
> gpa_t wall_clock;
>
> - struct page *ept_identity_pagetable;
> bool ept_identity_pagetable_done;
> gpa_t ept_identity_map_addr;
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 0918635e..5532ac8 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -741,6 +741,7 @@ static void vmx_sync_pir_to_irr_dummy(struct kvm_vcpu *vcpu);
> static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx);
> static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx);
> static bool vmx_mpx_supported(void);
> +static int alloc_identity_pagetable(struct kvm *kvm);
>
> static DEFINE_PER_CPU(struct vmcs *, vmxarea);
> static DEFINE_PER_CPU(struct vmcs *, current_vmcs);
> @@ -3921,21 +3922,21 @@ out:
>
> static int init_rmode_identity_map(struct kvm *kvm)
> {
> - int i, idx, r, ret;
> + int i, idx, r, ret = 0;
> pfn_t identity_map_pfn;
> u32 tmp;
>
> if (!enable_ept)
> return 1;
> - if (unlikely(!kvm->arch.ept_identity_pagetable)) {
> - printk(KERN_ERR "EPT: identity-mapping pagetable "
> - "haven't been allocated!\n");
> - return 0;
> - }
> if (likely(kvm->arch.ept_identity_pagetable_done))
> return 1;
> - ret = 0;
> identity_map_pfn = kvm->arch.ept_identity_map_addr>> PAGE_SHIFT;
> +
> + mutex_lock(&kvm->slots_lock);
> + r = alloc_identity_pagetable(kvm);
> + if (r)
> + goto out;

s/goto out/goto out2

Will resend the patch soon.

> +
> idx = srcu_read_lock(&kvm->srcu);
> r = kvm_clear_guest_page(kvm, identity_map_pfn, 0, PAGE_SIZE);
> if (r< 0)
> @@ -3953,6 +3954,9 @@ static int init_rmode_identity_map(struct kvm *kvm)
> ret = 1;
> out:
> srcu_read_unlock(&kvm->srcu, idx);
> +
> +out2:
> + mutex_unlock(&kvm->slots_lock);
> return ret;
> }
>
> @@ -4006,9 +4010,6 @@ static int alloc_identity_pagetable(struct kvm *kvm)
> struct kvm_userspace_memory_region kvm_userspace_mem;
> int r = 0;
>
> - mutex_lock(&kvm->slots_lock);
> - if (kvm->arch.ept_identity_pagetable)
> - goto out;
> kvm_userspace_mem.slot = IDENTITY_PAGETABLE_PRIVATE_MEMSLOT;
> kvm_userspace_mem.flags = 0;
> kvm_userspace_mem.guest_phys_addr =
> @@ -4025,9 +4026,7 @@ static int alloc_identity_pagetable(struct kvm *kvm)
> goto out;
> }
>
> - kvm->arch.ept_identity_pagetable = page;
> out:
> - mutex_unlock(&kvm->slots_lock);
> return r;
> }
>
> @@ -7583,8 +7582,6 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
> kvm->arch.ept_identity_map_addr =
> VMX_EPT_IDENTITY_PAGETABLE_ADDR;
> err = -ENOMEM;
> - if (alloc_identity_pagetable(kvm) != 0)
> - goto free_vmcs;
> if (!init_rmode_identity_map(kvm))
> goto free_vmcs;
> }