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[PATCH v4] cxl/test: Enforce PMD alignment for volatile mock regions

Richard Cheng posted 1 patch 1 week, 5 days ago 
tools/testing/cxl/test/cxl.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
[PATCH v4] cxl/test: Enforce PMD alignment for volatile mock regions
Posted by Richard Cheng 1 week, 5 days ago 
cxl_test allocates synthetic CFMWS HPA windows from a gen_pool with
SZ_256M alignment. On arm64 with CONFIG_ARM64_64K_PAGES=y and
CONFIG_PGTABLE_LEVELS=3, PMD_SIZE is 512M, so every CXL region carved
from a volatile window inherits a non-PMD-aligned start, and
cxl_dax_region_probe() -> alloc_dax_region() fails:

"""
    cxl_dax_region dax_region1: probe with driver cxl_dax_region failed
                                with error -12
"""

Enforce that every volatile mock CFMWS is PMD-aligned in both start and
size

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: Kai-Heng Feng <kaihengf@nvidia.com>
Signed-off-by: Richard Cheng <icheng@nvidia.com>
---
Changelog:

v3->v4:
    - Replace compile-time BUILD_BUG_ON() with runtime
      IS_ALIGNED(mock_auto_region_size, PMD_SIZE) check in
cxl_test_init().

v2->v3:
    - Correct hunk headers
    - Add base commit SHA

v1->v2:
    - Reframe from "fix start alignment" to "enforce PMD invariant for
      volatile CFMWS"
    - Bump cfmws5.window_size to max(SZ_256M, PMD_SIZE)
    - Gate populate_cedt() alignment on
      ACPI_CEDT_CFMWS_RESTRICT_VOLATILE so PMEM windows stay at SZ_256M
    - Add BUILD_BUG_ON for MOCK_AUTO_REGION_SIZE_DEFAULT v.s. PMD_SIZE
      in cxl_test_init()

Best regards,
Richard Cheng.
---
 tools/testing/cxl/test/cxl.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
index 418669927fb0..6f8fa7504cad 100644
--- a/tools/testing/cxl/test/cxl.c
+++ b/tools/testing/cxl/test/cxl.c
@@ -318,7 +318,7 @@ static struct {
 			.restrictions = ACPI_CEDT_CFMWS_RESTRICT_HOSTONLYMEM |
 					ACPI_CEDT_CFMWS_RESTRICT_VOLATILE,
 			.qtg_id = FAKE_QTG_ID,
-			.window_size = SZ_256M,
+			.window_size = SZ_256M > PMD_SIZE ? SZ_256M : PMD_SIZE,
 		},
 		.target = { 3 },
 	},
@@ -495,9 +495,12 @@ static int populate_cedt(void)
 
 	for (i = cfmws_start; i <= cfmws_end; i++) {
 		struct acpi_cedt_cfmws *window = mock_cfmws[i];
+		int align = SZ_256M;
 
 		cfmws_elc_update(window, i);
-		res = alloc_mock_res(window->window_size, SZ_256M);
+		if (window->restrictions & ACPI_CEDT_CFMWS_RESTRICT_VOLATILE)
+			align = max_t(int, SZ_256M, PMD_SIZE);
+		res = alloc_mock_res(window->window_size, align);
 		if (!res)
 			return -ENOMEM;
 		window->base_hpa = res->range.start;
@@ -1826,6 +1829,12 @@ static __init int cxl_test_init(void)
 	int rc, i;
 	struct range mappable;
 
+	if (!IS_ALIGNED(mock_auto_region_size, PMD_SIZE)) {
+		pr_err_once("mock_auto_region_size %d must be PMD-aligned\n",
+			    mock_auto_region_size);
+		return -EINVAL;
+	}
+
 	cxl_acpi_test();
 	cxl_core_test();
 	cxl_mem_test();

base-commit: 507bd4b66c85d5b65696150cc16d31ac0b2ab151
-- 
2.43.0
Re: [PATCH v4] cxl/test: Enforce PMD alignment for volatile mock regions
Posted by Dave Jiang 1 week, 4 days ago 

On 5/27/26 2:03 AM, Richard Cheng wrote:
> cxl_test allocates synthetic CFMWS HPA windows from a gen_pool with
> SZ_256M alignment. On arm64 with CONFIG_ARM64_64K_PAGES=y and
> CONFIG_PGTABLE_LEVELS=3, PMD_SIZE is 512M, so every CXL region carved
> from a volatile window inherits a non-PMD-aligned start, and
> cxl_dax_region_probe() -> alloc_dax_region() fails:
> 
> """
>     cxl_dax_region dax_region1: probe with driver cxl_dax_region failed
>                                 with error -12
> """
> 
> Enforce that every volatile mock CFMWS is PMD-aligned in both start and
> size
> 
> Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> Acked-by: Kai-Heng Feng <kaihengf@nvidia.com>
> Signed-off-by: Richard Cheng <icheng@nvidia.com>

Applied to cxl/next
8850852b25f7884d9804f8de5591edb3881bd674

> ---
> Changelog:
> 
> v3->v4:
>     - Replace compile-time BUILD_BUG_ON() with runtime
>       IS_ALIGNED(mock_auto_region_size, PMD_SIZE) check in
> cxl_test_init().
> 
> v2->v3:
>     - Correct hunk headers
>     - Add base commit SHA
> 
> v1->v2:
>     - Reframe from "fix start alignment" to "enforce PMD invariant for
>       volatile CFMWS"
>     - Bump cfmws5.window_size to max(SZ_256M, PMD_SIZE)
>     - Gate populate_cedt() alignment on
>       ACPI_CEDT_CFMWS_RESTRICT_VOLATILE so PMEM windows stay at SZ_256M
>     - Add BUILD_BUG_ON for MOCK_AUTO_REGION_SIZE_DEFAULT v.s. PMD_SIZE
>       in cxl_test_init()
> 
> Best regards,
> Richard Cheng.
> ---
>  tools/testing/cxl/test/cxl.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
> index 418669927fb0..6f8fa7504cad 100644
> --- a/tools/testing/cxl/test/cxl.c
> +++ b/tools/testing/cxl/test/cxl.c
> @@ -318,7 +318,7 @@ static struct {
>  			.restrictions = ACPI_CEDT_CFMWS_RESTRICT_HOSTONLYMEM |
>  					ACPI_CEDT_CFMWS_RESTRICT_VOLATILE,
>  			.qtg_id = FAKE_QTG_ID,
> -			.window_size = SZ_256M,
> +			.window_size = SZ_256M > PMD_SIZE ? SZ_256M : PMD_SIZE,
>  		},
>  		.target = { 3 },
>  	},
> @@ -495,9 +495,12 @@ static int populate_cedt(void)
>  
>  	for (i = cfmws_start; i <= cfmws_end; i++) {
>  		struct acpi_cedt_cfmws *window = mock_cfmws[i];
> +		int align = SZ_256M;
>  
>  		cfmws_elc_update(window, i);
> -		res = alloc_mock_res(window->window_size, SZ_256M);
> +		if (window->restrictions & ACPI_CEDT_CFMWS_RESTRICT_VOLATILE)
> +			align = max_t(int, SZ_256M, PMD_SIZE);
> +		res = alloc_mock_res(window->window_size, align);
>  		if (!res)
>  			return -ENOMEM;
>  		window->base_hpa = res->range.start;
> @@ -1826,6 +1829,12 @@ static __init int cxl_test_init(void)
>  	int rc, i;
>  	struct range mappable;
>  
> +	if (!IS_ALIGNED(mock_auto_region_size, PMD_SIZE)) {
> +		pr_err_once("mock_auto_region_size %d must be PMD-aligned\n",
> +			    mock_auto_region_size);
> +		return -EINVAL;
> +	}
> +
>  	cxl_acpi_test();
>  	cxl_core_test();
>  	cxl_mem_test();
> 
> base-commit: 507bd4b66c85d5b65696150cc16d31ac0b2ab151
Re: [PATCH v4] cxl/test: Enforce PMD alignment for volatile mock regions
Posted by Alison Schofield 1 week, 4 days ago 
On Wed, May 27, 2026 at 05:03:32PM +0800, Richard Cheng wrote:
> cxl_test allocates synthetic CFMWS HPA windows from a gen_pool with
> SZ_256M alignment. On arm64 with CONFIG_ARM64_64K_PAGES=y and
> CONFIG_PGTABLE_LEVELS=3, PMD_SIZE is 512M, so every CXL region carved
> from a volatile window inherits a non-PMD-aligned start, and
> cxl_dax_region_probe() -> alloc_dax_region() fails:
> 
> """
>     cxl_dax_region dax_region1: probe with driver cxl_dax_region failed
>                                 with error -12
> """
> 
> Enforce that every volatile mock CFMWS is PMD-aligned in both start and
> size
> 

checkpatch is emitting this complaint, that I believe is a false
positive, and I'm happy to ignore versus add ugly code to appease.

WARNING: Comparisons should place the constant on the right side of the test
#36: FILE: tools/testing/cxl/test/cxl.c:321:
+			.window_size = SZ_256M > PMD_SIZE ? SZ_256M : PMD_SIZE,


Reviewed-by: Alison Schofield <alison.schofield@intel.com>


> Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> Acked-by: Kai-Heng Feng <kaihengf@nvidia.com>
> Signed-off-by: Richard Cheng <icheng@nvidia.com>
> ---
> Changelog:
> 
> v3->v4:
>     - Replace compile-time BUILD_BUG_ON() with runtime
>       IS_ALIGNED(mock_auto_region_size, PMD_SIZE) check in
> cxl_test_init().
> 
> v2->v3:
>     - Correct hunk headers
>     - Add base commit SHA
> 
> v1->v2:
>     - Reframe from "fix start alignment" to "enforce PMD invariant for
>       volatile CFMWS"
>     - Bump cfmws5.window_size to max(SZ_256M, PMD_SIZE)
>     - Gate populate_cedt() alignment on
>       ACPI_CEDT_CFMWS_RESTRICT_VOLATILE so PMEM windows stay at SZ_256M
>     - Add BUILD_BUG_ON for MOCK_AUTO_REGION_SIZE_DEFAULT v.s. PMD_SIZE
>       in cxl_test_init()
> 
> Best regards,
> Richard Cheng.
> ---
>  tools/testing/cxl/test/cxl.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
> index 418669927fb0..6f8fa7504cad 100644
> --- a/tools/testing/cxl/test/cxl.c
> +++ b/tools/testing/cxl/test/cxl.c
> @@ -318,7 +318,7 @@ static struct {
>  			.restrictions = ACPI_CEDT_CFMWS_RESTRICT_HOSTONLYMEM |
>  					ACPI_CEDT_CFMWS_RESTRICT_VOLATILE,
>  			.qtg_id = FAKE_QTG_ID,
> -			.window_size = SZ_256M,
> +			.window_size = SZ_256M > PMD_SIZE ? SZ_256M : PMD_SIZE,
>  		},
>  		.target = { 3 },
>  	},
> @@ -495,9 +495,12 @@ static int populate_cedt(void)
>  
>  	for (i = cfmws_start; i <= cfmws_end; i++) {
>  		struct acpi_cedt_cfmws *window = mock_cfmws[i];
> +		int align = SZ_256M;
>  
>  		cfmws_elc_update(window, i);
> -		res = alloc_mock_res(window->window_size, SZ_256M);
> +		if (window->restrictions & ACPI_CEDT_CFMWS_RESTRICT_VOLATILE)
> +			align = max_t(int, SZ_256M, PMD_SIZE);
> +		res = alloc_mock_res(window->window_size, align);
>  		if (!res)
>  			return -ENOMEM;
>  		window->base_hpa = res->range.start;
> @@ -1826,6 +1829,12 @@ static __init int cxl_test_init(void)
>  	int rc, i;
>  	struct range mappable;
>  
> +	if (!IS_ALIGNED(mock_auto_region_size, PMD_SIZE)) {
> +		pr_err_once("mock_auto_region_size %d must be PMD-aligned\n",
> +			    mock_auto_region_size);
> +		return -EINVAL;
> +	}
> +
>  	cxl_acpi_test();
>  	cxl_core_test();
>  	cxl_mem_test();
> 
> base-commit: 507bd4b66c85d5b65696150cc16d31ac0b2ab151
> -- 
> 2.43.0
>
Re: [PATCH v4] cxl/test: Enforce PMD alignment for volatile mock regions
Posted by Richard Cheng 1 week, 4 days ago 
On Wed, May 27, 2026 at 06:05:44PM +0800, Alison Schofield wrote:
> On Wed, May 27, 2026 at 05:03:32PM +0800, Richard Cheng wrote:
> > cxl_test allocates synthetic CFMWS HPA windows from a gen_pool with
> > SZ_256M alignment. On arm64 with CONFIG_ARM64_64K_PAGES=y and
> > CONFIG_PGTABLE_LEVELS=3, PMD_SIZE is 512M, so every CXL region carved
> > from a volatile window inherits a non-PMD-aligned start, and
> > cxl_dax_region_probe() -> alloc_dax_region() fails:
> > 
> > """
> >     cxl_dax_region dax_region1: probe with driver cxl_dax_region failed
> >                                 with error -12
> > """
> > 
> > Enforce that every volatile mock CFMWS is PMD-aligned in both start and
> > size
> > 
> 
> checkpatch is emitting this complaint, that I believe is a false
> positive, and I'm happy to ignore versus add ugly code to appease.
> 
> WARNING: Comparisons should place the constant on the right side of the test
> #36: FILE: tools/testing/cxl/test/cxl.c:321:
> +			.window_size = SZ_256M > PMD_SIZE ? SZ_256M : PMD_SIZE,
> 
> 
> Reviewed-by: Alison Schofield <alison.schofield@intel.com>
> 
>

Hello Alison,

Thanks for your kindness,
I ran into issue when running checkpatch script, that's why I tried to edit the line in v2,
should have decleared that more clearly.

Thanks.
--Richard
 
> > Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> > Acked-by: Kai-Heng Feng <kaihengf@nvidia.com>
> > Signed-off-by: Richard Cheng <icheng@nvidia.com>
> > ---
> > Changelog:
> > 
> > v3->v4:
> >     - Replace compile-time BUILD_BUG_ON() with runtime
> >       IS_ALIGNED(mock_auto_region_size, PMD_SIZE) check in
> > cxl_test_init().
> > 
> > v2->v3:
> >     - Correct hunk headers
> >     - Add base commit SHA
> > 
> > v1->v2:
> >     - Reframe from "fix start alignment" to "enforce PMD invariant for
> >       volatile CFMWS"
> >     - Bump cfmws5.window_size to max(SZ_256M, PMD_SIZE)
> >     - Gate populate_cedt() alignment on
> >       ACPI_CEDT_CFMWS_RESTRICT_VOLATILE so PMEM windows stay at SZ_256M
> >     - Add BUILD_BUG_ON for MOCK_AUTO_REGION_SIZE_DEFAULT v.s. PMD_SIZE
> >       in cxl_test_init()
> > 
> > Best regards,
> > Richard Cheng.
> > ---
> >  tools/testing/cxl/test/cxl.c | 13 +++++++++++--
> >  1 file changed, 11 insertions(+), 2 deletions(-)
> > 
> > diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
> > index 418669927fb0..6f8fa7504cad 100644
> > --- a/tools/testing/cxl/test/cxl.c
> > +++ b/tools/testing/cxl/test/cxl.c
> > @@ -318,7 +318,7 @@ static struct {
> >  			.restrictions = ACPI_CEDT_CFMWS_RESTRICT_HOSTONLYMEM |
> >  					ACPI_CEDT_CFMWS_RESTRICT_VOLATILE,
> >  			.qtg_id = FAKE_QTG_ID,
> > -			.window_size = SZ_256M,
> > +			.window_size = SZ_256M > PMD_SIZE ? SZ_256M : PMD_SIZE,
> >  		},
> >  		.target = { 3 },
> >  	},
> > @@ -495,9 +495,12 @@ static int populate_cedt(void)
> >  
> >  	for (i = cfmws_start; i <= cfmws_end; i++) {
> >  		struct acpi_cedt_cfmws *window = mock_cfmws[i];
> > +		int align = SZ_256M;
> >  
> >  		cfmws_elc_update(window, i);
> > -		res = alloc_mock_res(window->window_size, SZ_256M);
> > +		if (window->restrictions & ACPI_CEDT_CFMWS_RESTRICT_VOLATILE)
> > +			align = max_t(int, SZ_256M, PMD_SIZE);
> > +		res = alloc_mock_res(window->window_size, align);
> >  		if (!res)
> >  			return -ENOMEM;
> >  		window->base_hpa = res->range.start;
> > @@ -1826,6 +1829,12 @@ static __init int cxl_test_init(void)
> >  	int rc, i;
> >  	struct range mappable;
> >  
> > +	if (!IS_ALIGNED(mock_auto_region_size, PMD_SIZE)) {
> > +		pr_err_once("mock_auto_region_size %d must be PMD-aligned\n",
> > +			    mock_auto_region_size);
> > +		return -EINVAL;
> > +	}
> > +
> >  	cxl_acpi_test();
> >  	cxl_core_test();
> >  	cxl_mem_test();
> > 
> > base-commit: 507bd4b66c85d5b65696150cc16d31ac0b2ab151
> > -- 
> > 2.43.0
> >

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