diff mbox series

[XEN,v7,08/20] xen/arm: ffa: note dependency on 4k pages

Message ID 6c0ef5d2174bfa8c25aeb94395160ab9d863b63a.1677079672.git.jens.wiklander@linaro.org (mailing list archive)
State Superseded
Headers show
Series Xen FF-A mediator | expand

Commit Message

Jens Wiklander Feb. 22, 2023, 3:33 p.m. UTC
Adds a BUILD_BUG_ON() to assert the dependency on 4k pages in the FF-A
mediator.

Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
---
 xen/arch/arm/tee/ffa.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

Comments

Bertrand Marquis Feb. 24, 2023, 3:27 p.m. UTC | #1
HI Jens,

> On 22 Feb 2023, at 16:33, Jens Wiklander <jens.wiklander@linaro.org> wrote:
> 
> Adds a BUILD_BUG_ON() to assert the dependency on 4k pages in the FF-A
> mediator.
> 
> Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

NIT: I would s/note/enforce/ in the title:
xen/arm: ffa: enforce 4k pages

Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>

Cheers
Bertrand

> ---
> xen/arch/arm/tee/ffa.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
> 
> diff --git a/xen/arch/arm/tee/ffa.c b/xen/arch/arm/tee/ffa.c
> index d04bac9cc47f..8b0b80ce1ff5 100644
> --- a/xen/arch/arm/tee/ffa.c
> +++ b/xen/arch/arm/tee/ffa.c
> @@ -56,6 +56,16 @@
> #define FFA_MY_VERSION          MAKE_FFA_VERSION(FFA_MY_VERSION_MAJOR, \
>                                                  FFA_MY_VERSION_MINOR)
> 
> +/*
> + * The FF-A specification explicitly works with 4K pages as a measure of
> + * memory size, for example, FFA_RXTX_MAP takes one parameter "RX/TX page
> + * count" which is the number of contiguous 4K pages allocated. Xen may use
> + * a different page size depending on the configuration to avoid confusion
> + * with PAGE_SIZE use a special define when it's a page size as in the FF-A
> + * specification.
> + */
> +#define FFA_PAGE_SIZE                   SZ_4K
> +
> /* Framework direct request/response */
> #define FFA_MSG_FLAG_FRAMEWORK          BIT(31, U)
> #define FFA_MSG_TYPE_MASK               0xFFU;
> @@ -242,6 +252,17 @@ static bool ffa_probe(void)
>     unsigned int major_vers;
>     unsigned int minor_vers;
> 
> +    /*
> +     * FF-A often works in units of 4K pages and currently it's assumed
> +     * that we can map memory using that granularity. See also the comment
> +     * above the FFA_PAGE_SIZE define.
> +     *
> +     * It is possible to support a PAGE_SIZE larger than 4K in Xen, but
> +     * until that is fully handled in this code make sure that we only use
> +     * 4K page sizes.
> +     */
> +    BUILD_BUG_ON(PAGE_SIZE != FFA_PAGE_SIZE);
> +
>     /*
>      * psci_init_smccc() updates this value with what's reported by EL-3
>      * or secure world.
> -- 
> 2.34.1
>
Jens Wiklander Feb. 28, 2023, 2:17 p.m. UTC | #2
Hi Bertrand,

On Fri, Feb 24, 2023 at 4:27 PM Bertrand Marquis
<Bertrand.Marquis@arm.com> wrote:
>
> HI Jens,
>
> > On 22 Feb 2023, at 16:33, Jens Wiklander <jens.wiklander@linaro.org> wrote:
> >
> > Adds a BUILD_BUG_ON() to assert the dependency on 4k pages in the FF-A
> > mediator.
> >
> > Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
>
> NIT: I would s/note/enforce/ in the title:
> xen/arm: ffa: enforce 4k pages

OK, I'll fix it.

Thanks,
Jens

>
> Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
>
> Cheers
> Bertrand
>
> > ---
> > xen/arch/arm/tee/ffa.c | 21 +++++++++++++++++++++
> > 1 file changed, 21 insertions(+)
> >
> > diff --git a/xen/arch/arm/tee/ffa.c b/xen/arch/arm/tee/ffa.c
> > index d04bac9cc47f..8b0b80ce1ff5 100644
> > --- a/xen/arch/arm/tee/ffa.c
> > +++ b/xen/arch/arm/tee/ffa.c
> > @@ -56,6 +56,16 @@
> > #define FFA_MY_VERSION          MAKE_FFA_VERSION(FFA_MY_VERSION_MAJOR, \
> >                                                  FFA_MY_VERSION_MINOR)
> >
> > +/*
> > + * The FF-A specification explicitly works with 4K pages as a measure of
> > + * memory size, for example, FFA_RXTX_MAP takes one parameter "RX/TX page
> > + * count" which is the number of contiguous 4K pages allocated. Xen may use
> > + * a different page size depending on the configuration to avoid confusion
> > + * with PAGE_SIZE use a special define when it's a page size as in the FF-A
> > + * specification.
> > + */
> > +#define FFA_PAGE_SIZE                   SZ_4K
> > +
> > /* Framework direct request/response */
> > #define FFA_MSG_FLAG_FRAMEWORK          BIT(31, U)
> > #define FFA_MSG_TYPE_MASK               0xFFU;
> > @@ -242,6 +252,17 @@ static bool ffa_probe(void)
> >     unsigned int major_vers;
> >     unsigned int minor_vers;
> >
> > +    /*
> > +     * FF-A often works in units of 4K pages and currently it's assumed
> > +     * that we can map memory using that granularity. See also the comment
> > +     * above the FFA_PAGE_SIZE define.
> > +     *
> > +     * It is possible to support a PAGE_SIZE larger than 4K in Xen, but
> > +     * until that is fully handled in this code make sure that we only use
> > +     * 4K page sizes.
> > +     */
> > +    BUILD_BUG_ON(PAGE_SIZE != FFA_PAGE_SIZE);
> > +
> >     /*
> >      * psci_init_smccc() updates this value with what's reported by EL-3
> >      * or secure world.
> > --
> > 2.34.1
> >
>
diff mbox series

Patch

diff --git a/xen/arch/arm/tee/ffa.c b/xen/arch/arm/tee/ffa.c
index d04bac9cc47f..8b0b80ce1ff5 100644
--- a/xen/arch/arm/tee/ffa.c
+++ b/xen/arch/arm/tee/ffa.c
@@ -56,6 +56,16 @@ 
 #define FFA_MY_VERSION          MAKE_FFA_VERSION(FFA_MY_VERSION_MAJOR, \
                                                  FFA_MY_VERSION_MINOR)
 
+/*
+ * The FF-A specification explicitly works with 4K pages as a measure of
+ * memory size, for example, FFA_RXTX_MAP takes one parameter "RX/TX page
+ * count" which is the number of contiguous 4K pages allocated. Xen may use
+ * a different page size depending on the configuration to avoid confusion
+ * with PAGE_SIZE use a special define when it's a page size as in the FF-A
+ * specification.
+ */
+#define FFA_PAGE_SIZE                   SZ_4K
+
 /* Framework direct request/response */
 #define FFA_MSG_FLAG_FRAMEWORK          BIT(31, U)
 #define FFA_MSG_TYPE_MASK               0xFFU;
@@ -242,6 +252,17 @@  static bool ffa_probe(void)
     unsigned int major_vers;
     unsigned int minor_vers;
 
+    /*
+     * FF-A often works in units of 4K pages and currently it's assumed
+     * that we can map memory using that granularity. See also the comment
+     * above the FFA_PAGE_SIZE define.
+     *
+     * It is possible to support a PAGE_SIZE larger than 4K in Xen, but
+     * until that is fully handled in this code make sure that we only use
+     * 4K page sizes.
+     */
+    BUILD_BUG_ON(PAGE_SIZE != FFA_PAGE_SIZE);
+
     /*
      * psci_init_smccc() updates this value with what's reported by EL-3
      * or secure world.