[v8,14/16] x86/virt/tdx: Initialize all TDMRs

Commit Message

Huang, Kai Dec. 9, 2022, 6:52 a.m. UTC

After the global KeyID has been configured on all packages, initialize
all TDMRs to make all TDX-usable memory regions that are passed to the
TDX module become usable.

This is the last step of initializing the TDX module.

Initializing different TDMRs can be parallelized.  For now to keep it
simple, just initialize all TDMRs one by one.  It can be enhanced in the
future.

Reviewed-by: Isaku Yamahata <[e-mail]>
Signed-off-by: Kai Huang <[e-mail]>
---

v7 -> v8: (Dave)
 - Changelog:
   - explicitly call out this is the last step of TDX module initialization.
   - Trimed down changelog by removing SEAMCALL name and details.
 - Removed/trimmed down unnecessary comments.
 - Other changes due to 'struct tdmr_info_list'.

v6 -> v7:
 - Removed need_resched() check. -- Andi.

---
 arch/x86/virt/vmx/tdx/tdx.c | 61 ++++++++++++++++++++++++++++++++-----
 arch/x86/virt/vmx/tdx/tdx.h |  1 +
 2 files changed, 54 insertions(+), 8 deletions(-)

Comments

Dave Hansen Jan. 7, 2023, 12:17 a.m. UTC | #1

On 12/8/22 22:52, Kai Huang wrote:
> After the global KeyID has been configured on all packages, initialize
> all TDMRs to make all TDX-usable memory regions that are passed to the
> TDX module become usable.
> 
> This is the last step of initializing the TDX module.
> 
> Initializing different TDMRs can be parallelized.  For now to keep it
> simple, just initialize all TDMRs one by one.  It can be enhanced in the
> future.

The changelog probably also needs a note about this being a long process
and also at least touching on *why* it takes so long.

> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index 4c779e8412f1..8b7314f19df2 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -1006,6 +1006,55 @@ static int config_global_keyid(void)
>  	return ret;
>  }
>  
> +static int init_tdmr(struct tdmr_info *tdmr)
> +{
> +	u64 next;
> +
> +	/*
> +	 * Initializing a TDMR can be time consuming.  To avoid long
> +	 * SEAMCALLs, the TDX module may only initialize a part of the
> +	 * TDMR in each call.
> +	 */
> +	do {
> +		struct tdx_module_output out;
> +		int ret;
> +
> +		/* All 0's are unused parameters, they mean nothing. */
> +		ret = seamcall(TDH_SYS_TDMR_INIT, tdmr->base, 0, 0, 0, NULL,
> +				&out);
> +		if (ret)
> +			return ret;
> +		/*
> +		 * RDX contains 'next-to-initialize' address if
> +		 * TDH.SYS.TDMR.INT succeeded.

This reads strangely.  "Success" to me really is different from "partial
success".  Sure, partial success is also not an error, *but* this can be
explained better.  How about:

		 * RDX contains 'next-to-initialize' address if
		 * TDH.SYS.TDMR.INT did not fully complete and should
		 * be retried.


> +		 */
> +		next = out.rdx;
> +		cond_resched();
> +		/* Keep making SEAMCALLs until the TDMR is done */
> +	} while (next < tdmr->base + tdmr->size);
> +
> +	return 0;
> +}
> +
> +static int init_tdmrs(struct tdmr_info_list *tdmr_list)
> +{
> +	int i;
> +
> +	/*
> +	 * This operation is costly.  It can be parallelized,
> +	 * but keep it simple for now.
> +	 */
> +	for (i = 0; i < tdmr_list->nr_tdmrs; i++) {
> +		int ret;
> +
> +		ret = init_tdmr(tdmr_entry(tdmr_list, i));
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
>  static int init_tdx_module(void)
>  {
>  	/*
> @@ -1076,14 +1125,10 @@ static int init_tdx_module(void)
>  	if (ret)
>  		goto out_free_pamts;
>  
> -	/*
> -	 * TODO:
> -	 *
> -	 *  - Initialize all TDMRs.
> -	 *
> -	 *  Return error before all steps are done.
> -	 */
> -	ret = -EINVAL;
> +	/* Initialize TDMRs to complete the TDX module initialization */
> +	ret = init_tdmrs(&tdmr_list);
> +	if (ret)
> +		goto out_free_pamts;
>  out_free_pamts:
>  	if (ret) {
>  		/*
> diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
> index f5c12a2543d4..163c4876dee4 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.h
> +++ b/arch/x86/virt/vmx/tdx/tdx.h
> @@ -21,6 +21,7 @@
>   */
>  #define TDH_SYS_KEY_CONFIG	31
>  #define TDH_SYS_INFO		32
> +#define TDH_SYS_TDMR_INIT	36
>  #define TDH_SYS_CONFIG		45
>  
>  struct cmr_info {

Huang, Kai Jan. 10, 2023, 10:23 a.m. UTC | #2

On Fri, 2023-01-06 at 16:17 -0800, Dave Hansen wrote:
> On 12/8/22 22:52, Kai Huang wrote:
> > After the global KeyID has been configured on all packages, initialize
> > all TDMRs to make all TDX-usable memory regions that are passed to the
> > TDX module become usable.
> > 
> > This is the last step of initializing the TDX module.
> > 
> > Initializing different TDMRs can be parallelized.  For now to keep it
> > simple, just initialize all TDMRs one by one.  It can be enhanced in the
> > future.
> 
> The changelog probably also needs a note about this being a long process
> and also at least touching on *why* it takes so long.

Will add.  How about:

	Initializing TDMRs can be time consuming on large memory systems as it 
	involves initializing all metadata entries for all pages that can be 
	used by TDX guests.

And put it before "Initializing different TDMRs can be parallelized ..."?

> 
> > diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> > index 4c779e8412f1..8b7314f19df2 100644
> > --- a/arch/x86/virt/vmx/tdx/tdx.c
> > +++ b/arch/x86/virt/vmx/tdx/tdx.c
> > @@ -1006,6 +1006,55 @@ static int config_global_keyid(void)
> >  	return ret;
> >  }
> >  
> > +static int init_tdmr(struct tdmr_info *tdmr)
> > +{
> > +	u64 next;
> > +
> > +	/*
> > +	 * Initializing a TDMR can be time consuming.  To avoid long
> > +	 * SEAMCALLs, the TDX module may only initialize a part of the
> > +	 * TDMR in each call.
> > +	 */
> > +	do {
> > +		struct tdx_module_output out;
> > +		int ret;
> > +
> > +		/* All 0's are unused parameters, they mean nothing. */
> > +		ret = seamcall(TDH_SYS_TDMR_INIT, tdmr->base, 0, 0, 0, NULL,
> > +				&out);
> > +		if (ret)
> > +			return ret;
> > +		/*
> > +		 * RDX contains 'next-to-initialize' address if
> > +		 * TDH.SYS.TDMR.INT succeeded.
> 
> This reads strangely.  "Success" to me really is different from "partial
> success".  Sure, partial success is also not an error, *but* this can be
> explained better.  How about:
> 
> 		 * RDX contains 'next-to-initialize' address if
> 		 * TDH.SYS.TDMR.INT did not fully complete and should
> 		 * be retried.
> 

Will do.

[snip]

Patch

diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 4c779e8412f1..8b7314f19df2 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -1006,6 +1006,55 @@  static int config_global_keyid(void)
 	return ret;
 }
 
+static int init_tdmr(struct tdmr_info *tdmr)
+{
+	u64 next;
+
+	/*
+	 * Initializing a TDMR can be time consuming.  To avoid long
+	 * SEAMCALLs, the TDX module may only initialize a part of the
+	 * TDMR in each call.
+	 */
+	do {
+		struct tdx_module_output out;
+		int ret;
+
+		/* All 0's are unused parameters, they mean nothing. */
+		ret = seamcall(TDH_SYS_TDMR_INIT, tdmr->base, 0, 0, 0, NULL,
+				&out);
+		if (ret)
+			return ret;
+		/*
+		 * RDX contains 'next-to-initialize' address if
+		 * TDH.SYS.TDMR.INT succeeded.
+		 */
+		next = out.rdx;
+		cond_resched();
+		/* Keep making SEAMCALLs until the TDMR is done */
+	} while (next < tdmr->base + tdmr->size);
+
+	return 0;
+}
+
+static int init_tdmrs(struct tdmr_info_list *tdmr_list)
+{
+	int i;
+
+	/*
+	 * This operation is costly.  It can be parallelized,
+	 * but keep it simple for now.
+	 */
+	for (i = 0; i < tdmr_list->nr_tdmrs; i++) {
+		int ret;
+
+		ret = init_tdmr(tdmr_entry(tdmr_list, i));
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 static int init_tdx_module(void)
 {
 	/*
@@ -1076,14 +1125,10 @@  static int init_tdx_module(void)
 	if (ret)
 		goto out_free_pamts;
 
-	/*
-	 * TODO:
-	 *
-	 *  - Initialize all TDMRs.
-	 *
-	 *  Return error before all steps are done.
-	 */
-	ret = -EINVAL;
+	/* Initialize TDMRs to complete the TDX module initialization */
+	ret = init_tdmrs(&tdmr_list);
+	if (ret)
+		goto out_free_pamts;
 out_free_pamts:
 	if (ret) {
 		/*
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index f5c12a2543d4..163c4876dee4 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -21,6 +21,7 @@ 
  */
 #define TDH_SYS_KEY_CONFIG	31
 #define TDH_SYS_INFO		32
+#define TDH_SYS_TDMR_INIT	36
 #define TDH_SYS_CONFIG		45
 
 struct cmr_info {