[PATCH v4 10/16] KVM: TDX: Allocate PAMT memory for vCPU control structures

Rick Edgecombe posted 16 patches 1 week, 4 days ago
[PATCH v4 10/16] KVM: TDX: Allocate PAMT memory for vCPU control structures
Posted by Rick Edgecombe 1 week, 4 days ago
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

TDX vCPU control structures are provided to the TDX module at 4KB page
size and require PAMT backing. This means for Dynamic PAMT they need to
also have 4KB backings installed.

Previous changes introduced tdx_alloc_page()/tdx_free_page() that can
allocate a page and automatically handle the DPAMT maintenance. Use them
for vCPU control structures instead of alloc_page()/__free_page().

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[update log]
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
v3:
 - Write log. Reame from “Allocate PAMT memory for TDH.VP.CREATE and
   TDH.VP.ADDCX”.
 - Remove new line damage
---
 arch/x86/kvm/vmx/tdx.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 8c4c1221e311..b6d7f4b5f40f 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -2882,7 +2882,7 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
 	int ret, i;
 	u64 err;
 
-	page = alloc_page(GFP_KERNEL);
+	page = tdx_alloc_page();
 	if (!page)
 		return -ENOMEM;
 	tdx->vp.tdvpr_page = page;
@@ -2902,7 +2902,7 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
 	}
 
 	for (i = 0; i < kvm_tdx->td.tdcx_nr_pages; i++) {
-		page = alloc_page(GFP_KERNEL);
+		page = tdx_alloc_page();
 		if (!page) {
 			ret = -ENOMEM;
 			goto free_tdcx;
@@ -2924,7 +2924,7 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
 			 * method, but the rest are freed here.
 			 */
 			for (; i < kvm_tdx->td.tdcx_nr_pages; i++) {
-				__free_page(tdx->vp.tdcx_pages[i]);
+				tdx_free_page(tdx->vp.tdcx_pages[i]);
 				tdx->vp.tdcx_pages[i] = NULL;
 			}
 			return -EIO;
@@ -2952,16 +2952,14 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
 
 free_tdcx:
 	for (i = 0; i < kvm_tdx->td.tdcx_nr_pages; i++) {
-		if (tdx->vp.tdcx_pages[i])
-			__free_page(tdx->vp.tdcx_pages[i]);
+		tdx_free_page(tdx->vp.tdcx_pages[i]);
 		tdx->vp.tdcx_pages[i] = NULL;
 	}
 	kfree(tdx->vp.tdcx_pages);
 	tdx->vp.tdcx_pages = NULL;
 
 free_tdvpr:
-	if (tdx->vp.tdvpr_page)
-		__free_page(tdx->vp.tdvpr_page);
+	tdx_free_page(tdx->vp.tdvpr_page);
 	tdx->vp.tdvpr_page = NULL;
 	tdx->vp.tdvpr_pa = 0;
 
-- 
2.51.2

Re: [PATCH v4 10/16] KVM: TDX: Allocate PAMT memory for vCPU control structures
Posted by Binbin Wu 6 days, 16 hours ago

On 11/21/2025 8:51 AM, Rick Edgecombe wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>
> TDX vCPU control structures are provided to the TDX module at 4KB page
> size and require PAMT backing. This means for Dynamic PAMT they need to
> also have 4KB backings installed.
>
> Previous changes introduced tdx_alloc_page()/tdx_free_page() that can
> allocate a page and automatically handle the DPAMT maintenance. Use them
> for vCPU control structures instead of alloc_page()/__free_page().
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> [update log]
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>

Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>

> ---
> v3:
>   - Write log. Reame from “Allocate PAMT memory for TDH.VP.CREATE and
>     TDH.VP.ADDCX”.
>   - Remove new line damage
> ---
>   arch/x86/kvm/vmx/tdx.c | 12 +++++-------
>   1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 8c4c1221e311..b6d7f4b5f40f 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -2882,7 +2882,7 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
>   	int ret, i;
>   	u64 err;
>   
> -	page = alloc_page(GFP_KERNEL);
> +	page = tdx_alloc_page();
>   	if (!page)
>   		return -ENOMEM;
>   	tdx->vp.tdvpr_page = page;
> @@ -2902,7 +2902,7 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
>   	}
>   
>   	for (i = 0; i < kvm_tdx->td.tdcx_nr_pages; i++) {
> -		page = alloc_page(GFP_KERNEL);
> +		page = tdx_alloc_page();
>   		if (!page) {
>   			ret = -ENOMEM;
>   			goto free_tdcx;
> @@ -2924,7 +2924,7 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
>   			 * method, but the rest are freed here.
>   			 */
>   			for (; i < kvm_tdx->td.tdcx_nr_pages; i++) {
> -				__free_page(tdx->vp.tdcx_pages[i]);
> +				tdx_free_page(tdx->vp.tdcx_pages[i]);
>   				tdx->vp.tdcx_pages[i] = NULL;
>   			}
>   			return -EIO;
> @@ -2952,16 +2952,14 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
>   
>   free_tdcx:
>   	for (i = 0; i < kvm_tdx->td.tdcx_nr_pages; i++) {
> -		if (tdx->vp.tdcx_pages[i])
> -			__free_page(tdx->vp.tdcx_pages[i]);
> +		tdx_free_page(tdx->vp.tdcx_pages[i]);
>   		tdx->vp.tdcx_pages[i] = NULL;
>   	}
>   	kfree(tdx->vp.tdcx_pages);
>   	tdx->vp.tdcx_pages = NULL;
>   
>   free_tdvpr:
> -	if (tdx->vp.tdvpr_page)
> -		__free_page(tdx->vp.tdvpr_page);
> +	tdx_free_page(tdx->vp.tdvpr_page);
>   	tdx->vp.tdvpr_page = NULL;
>   	tdx->vp.tdvpr_pa = 0;
>