Re: [RFC PATCH v4 08/16] KVM: TDX: Pin pages via get_page() right before ADD/AUG'ed to TDs

[Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx>]

On 7/26/2023 6:23 AM, isaku.yamahata@xxxxxxxxx wrote:
> From: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
>
> When kvm_faultin_pfn(), it doesn't have the info regarding which page level
> will the gfn be mapped at. Hence it doesn't know to pin a 4K page or a
> 2M page.
>
> Move the guest private pages pinning logic right before
> TDH_MEM_PAGE_ADD/AUG() since at that time it knows the page level info.
The code change of the patch doesn't match the changelog.

> Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> ---
>   arch/x86/kvm/vmx/tdx.c | 15 ++++++++-------
>   1 file changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index c122160142fd..bd1582e6b693 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -1361,7 +1361,8 @@ static void tdx_measure_page(struct kvm_tdx *kvm_tdx, hpa_t gpa, int size)
>   	}
>   }
>   
> -static void tdx_unpin(struct kvm *kvm, kvm_pfn_t pfn, int level)
> +static void tdx_unpin(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn,
> +		      enum pg_level level)
>   {
>   	int i;
>   
> @@ -1397,12 +1398,12 @@ static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
>   	if (likely(is_td_finalized(kvm_tdx))) {
>   		err = tdh_mem_page_aug(kvm_tdx->tdr_pa, gpa, tdx_level, hpa, &out);
>   		if (unlikely(err == TDX_ERROR_SEPT_BUSY)) {
> -			tdx_unpin(kvm, pfn, level);
> +			tdx_unpin(kvm, gfn, pfn, level);
>   			return -EAGAIN;
>   		}
>   		if (KVM_BUG_ON(err, kvm)) {
>   			pr_tdx_error(TDH_MEM_PAGE_AUG, err, &out);
> -			tdx_unpin(kvm, pfn, level);
> +			tdx_unpin(kvm, gfn, pfn, level);
>   			return -EIO;
>   		}
>   		return 0;
> @@ -1425,7 +1426,7 @@ static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
>   	 * always uses vcpu 0's page table and protected by vcpu->mutex).
>   	 */
>   	if (KVM_BUG_ON(kvm_tdx->source_pa == INVALID_PAGE, kvm)) {
> -		tdx_unpin(kvm, pfn, level);
> +		tdx_unpin(kvm, gfn, pfn, level);
>   		return -EINVAL;
>   	}
>   
> @@ -1443,7 +1444,7 @@ static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
>   	} while (unlikely(err == TDX_ERROR_SEPT_BUSY));
>   	if (KVM_BUG_ON(err, kvm)) {
>   		pr_tdx_error(TDH_MEM_PAGE_ADD, err, &out);
> -		tdx_unpin(kvm, pfn, level);
> +		tdx_unpin(kvm, gfn, pfn, level);
>   		return -EIO;
>   	} else if (measure)
>   		tdx_measure_page(kvm_tdx, gpa, KVM_HPAGE_SIZE(level));
> @@ -1472,7 +1473,7 @@ static int tdx_sept_drop_private_spte(struct kvm *kvm, gfn_t gfn,
>   		err = tdx_reclaim_page(hpa, level, false, 0);
>   		if (KVM_BUG_ON(err, kvm))
>   			return -EIO;
> -		tdx_unpin(kvm, pfn, level);
> +		tdx_unpin(kvm, gfn, pfn, level);
>   		return 0;
>   	}
>   
> @@ -1505,7 +1506,7 @@ static int tdx_sept_drop_private_spte(struct kvm *kvm, gfn_t gfn,
>   			r = -EIO;
>   		} else {
>   			tdx_clear_page(hpa, PAGE_SIZE);
> -			tdx_unpin(kvm, pfn + i, PG_LEVEL_4K);
> +			tdx_unpin(kvm, gfn + i, pfn + i, PG_LEVEL_4K);
>   		}
>   		hpa += PAGE_SIZE;
>   	}