We expose the shared memory to the domU using the "xen,shared-memory-v1"
reserved-memory binding. See
Documentation/devicetree/bindings/reserved-memory/xen,shared-memory.txt
in Linux for the corresponding device tree binding.
To save the cost of re-parsing shared memory device tree configuration when
creating shared memory nodes in guest device tree, this commit adds new field
"shm_mem" to store shm-info per domain.
For each shared memory region, a range is exposed under
the /reserved-memory node as a child node. Each range sub-node is
named xen-shmem@<address> and has the following properties:
- compatible:
compatible = "xen,shared-memory-v1"
- reg:
the base guest physical address and size of the shared memory region
- xen,id:
a string that identifies the shared memory region.
Signed-off-by: Penny Zheng <penny.zheng@arm.com>
---
v2 change:
- using xzalloc
- shm_id should be uint8_t
- make reg a local variable
- add #address-cells and #size-cells properties
- fix alignment
---
xen/arch/arm/domain_build.c | 144 ++++++++++++++++++++++++++++++
xen/arch/arm/include/asm/domain.h | 1 +
xen/arch/arm/include/asm/setup.h | 1 +
3 files changed, 146 insertions(+)
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 8d299a3616..f08606d2c0 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -894,6 +894,26 @@ static int __init allocate_shared_memory(struct domain *d,
return ret;
}
+static int __init append_shm_bank_to_domain(struct domain *d,
+ paddr_t start, paddr_t size,
+ u32 shm_id)
+{
+ /* Allocate memory at first insertion. */
+ if ( d->arch.shm_mem == NULL )
+ {
+ d->arch.shm_mem = xzalloc(struct meminfo);
+ if ( d->arch.shm_mem == NULL )
+ return -ENOMEM;
+ }
+
+ d->arch.shm_mem->bank[d->arch.shm_mem->nr_banks].start = start;
+ d->arch.shm_mem->bank[d->arch.shm_mem->nr_banks].size = size;
+ d->arch.shm_mem->bank[d->arch.shm_mem->nr_banks].shm_id = shm_id;
+ d->arch.shm_mem->nr_banks++;
+
+ return 0;
+}
+
static int __init process_shm(struct domain *d,
const struct dt_device_node *node)
{
@@ -975,6 +995,14 @@ static int __init process_shm(struct domain *d,
if ( ret )
return ret;
}
+
+ /*
+ * Record static shared memory region info for later setting
+ * up shm-node in guest device tree.
+ */
+ ret = append_shm_bank_to_domain(d, gbase, psize, shm_id);
+ if ( ret )
+ return ret;
}
return 0;
@@ -1305,6 +1333,117 @@ static int __init make_memory_node(const struct domain *d,
return res;
}
+#ifdef CONFIG_STATIC_SHM
+static int __init make_shm_memory_node(const struct domain *d,
+ void *fdt,
+ int addrcells, int sizecells,
+ struct meminfo *mem)
+{
+ unsigned long i = 0;
+ int res = 0;
+
+ if ( mem->nr_banks == 0 )
+ return -ENOENT;
+
+ /*
+ * For each shared memory region, a range is exposed under
+ * the /reserved-memory node as a child node. Each range sub-node is
+ * named xen-shmem@<address>.
+ */
+ dt_dprintk("Create xen-shmem node\n");
+
+ for ( ; i < mem->nr_banks; i++ )
+ {
+ uint64_t start = mem->bank[i].start;
+ uint64_t size = mem->bank[i].size;
+ uint8_t shm_id = mem->bank[i].shm_id;
+ /* Placeholder for xen-shmem@ + a 64-bit number + \0 */
+ char buf[27];
+ const char compat[] = "xen,shared-memory-v1";
+ __be32 reg[4];
+ __be32 *cells;
+ unsigned int len = (addrcells + sizecells) * sizeof(__be32);
+
+ snprintf(buf, sizeof(buf), "xen-shmem@%"PRIx64, mem->bank[i].start);
+ res = fdt_begin_node(fdt, buf);
+ if ( res )
+ return res;
+
+ res = fdt_property(fdt, "compatible", compat, sizeof(compat));
+ if ( res )
+ return res;
+
+ cells = reg;
+ dt_child_set_range(&cells, addrcells, sizecells, start, size);
+
+ res = fdt_property(fdt, "reg", reg, len);
+ if ( res )
+ return res;
+
+ dt_dprintk("Shared memory bank %lu: %#"PRIx64"->%#"PRIx64"\n",
+ i, start, start + size);
+
+ res = fdt_property_cell(fdt, "xen,id", shm_id);
+ if ( res )
+ return res;
+
+ res = fdt_end_node(fdt);
+ if ( res )
+ return res;
+ }
+
+ return res;
+}
+#else
+static int __init make_shm_memory_node(const struct domain *d,
+ void *fdt,
+ int addrcells, int sizecells,
+ struct meminfo *mem)
+{
+ ASSERT_UNREACHABLE();
+}
+#endif
+
+static int __init make_resv_memory_node(const struct domain *d,
+ void *fdt,
+ int addrcells, int sizecells,
+ struct meminfo *mem)
+{
+ int res = 0;
+ /* Placeholder for reserved-memory\0 */
+ char resvbuf[16] = "reserved-memory";
+
+ if ( mem == NULL )
+ /* No shared memory provided. */
+ return 0;
+
+ dt_dprintk("Create reserved-memory node\n");
+
+ res = fdt_begin_node(fdt, resvbuf);
+ if ( res )
+ return res;
+
+ res = fdt_property(fdt, "ranges", NULL, 0);
+ if ( res )
+ return res;
+
+ res = fdt_property_cell(fdt, "#address-cells", addrcells);
+ if ( res )
+ return res;
+
+ res = fdt_property_cell(fdt, "#size-cells", sizecells);
+ if ( res )
+ return res;
+
+ res = make_shm_memory_node(d, fdt, addrcells, sizecells, mem);
+ if ( res )
+ return res;
+
+ res = fdt_end_node(fdt);
+
+ return res;
+}
+
static int __init add_ext_regions(unsigned long s, unsigned long e, void *data)
{
struct meminfo *ext_regions = data;
@@ -3041,6 +3180,11 @@ static int __init prepare_dtb_domU(struct domain *d, struct kernel_info *kinfo)
if ( ret )
goto err;
+ ret = make_resv_memory_node(d, kinfo->fdt, addrcells, sizecells,
+ d->arch.shm_mem);
+ if ( ret )
+ goto err;
+
/*
* domain_handle_dtb_bootmodule has to be called before the rest of
* the device tree is generated because it depends on the value of
diff --git a/xen/arch/arm/include/asm/domain.h b/xen/arch/arm/include/asm/domain.h
index ed63c2b6f9..d0d1e12cfe 100644
--- a/xen/arch/arm/include/asm/domain.h
+++ b/xen/arch/arm/include/asm/domain.h
@@ -104,6 +104,7 @@ struct arch_domain
#endif
bool directmap;
+ struct meminfo *shm_mem;
} __cacheline_aligned;
struct arch_vcpu
diff --git a/xen/arch/arm/include/asm/setup.h b/xen/arch/arm/include/asm/setup.h
index 38e02ced36..b5909acf68 100644
--- a/xen/arch/arm/include/asm/setup.h
+++ b/xen/arch/arm/include/asm/setup.h
@@ -29,6 +29,7 @@ struct membank {
bool xen_domain; /* whether the memory bank is bound to a Xen domain. */
#ifdef CONFIG_STATIC_SHM
unsigned long nr_shm_domain;
+ uint8_t shm_id ; /* ID identifier of a static shared memory bank. */
#endif
};
--
2.25.1On Fri, 6 May 2022, Penny Zheng wrote:
> We expose the shared memory to the domU using the "xen,shared-memory-v1"
> reserved-memory binding. See
> Documentation/devicetree/bindings/reserved-memory/xen,shared-memory.txt
> in Linux for the corresponding device tree binding.
>
> To save the cost of re-parsing shared memory device tree configuration when
> creating shared memory nodes in guest device tree, this commit adds new field
> "shm_mem" to store shm-info per domain.
>
> For each shared memory region, a range is exposed under
> the /reserved-memory node as a child node. Each range sub-node is
> named xen-shmem@<address> and has the following properties:
> - compatible:
> compatible = "xen,shared-memory-v1"
> - reg:
> the base guest physical address and size of the shared memory region
> - xen,id:
> a string that identifies the shared memory region.
>
> Signed-off-by: Penny Zheng <penny.zheng@arm.com>
> ---
> v2 change:
> - using xzalloc
> - shm_id should be uint8_t
> - make reg a local variable
> - add #address-cells and #size-cells properties
> - fix alignment
> ---
> xen/arch/arm/domain_build.c | 144 ++++++++++++++++++++++++++++++
> xen/arch/arm/include/asm/domain.h | 1 +
> xen/arch/arm/include/asm/setup.h | 1 +
> 3 files changed, 146 insertions(+)
>
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 8d299a3616..f08606d2c0 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -894,6 +894,26 @@ static int __init allocate_shared_memory(struct domain *d,
> return ret;
> }
>
> +static int __init append_shm_bank_to_domain(struct domain *d,
> + paddr_t start, paddr_t size,
> + u32 shm_id)
> +{
> + /* Allocate memory at first insertion. */
> + if ( d->arch.shm_mem == NULL )
> + {
> + d->arch.shm_mem = xzalloc(struct meminfo);
> + if ( d->arch.shm_mem == NULL )
> + return -ENOMEM;
> + }
> +
> + d->arch.shm_mem->bank[d->arch.shm_mem->nr_banks].start = start;
> + d->arch.shm_mem->bank[d->arch.shm_mem->nr_banks].size = size;
> + d->arch.shm_mem->bank[d->arch.shm_mem->nr_banks].shm_id = shm_id;
> + d->arch.shm_mem->nr_banks++;
> +
> + return 0;
> +}
Can we call xfree(d->arch.shm_mem) at domain destruction?
Even better, we might be able to call it earlier, soon after the
make_resv_memory_node() call because we don't need it any longer after
that?
> static int __init process_shm(struct domain *d,
> const struct dt_device_node *node)
> {
> @@ -975,6 +995,14 @@ static int __init process_shm(struct domain *d,
> if ( ret )
> return ret;
> }
> +
> + /*
> + * Record static shared memory region info for later setting
> + * up shm-node in guest device tree.
> + */
> + ret = append_shm_bank_to_domain(d, gbase, psize, shm_id);
> + if ( ret )
> + return ret;
> }
>
> return 0;
> @@ -1305,6 +1333,117 @@ static int __init make_memory_node(const struct domain *d,
> return res;
> }
>
> +#ifdef CONFIG_STATIC_SHM
> +static int __init make_shm_memory_node(const struct domain *d,
> + void *fdt,
> + int addrcells, int sizecells,
> + struct meminfo *mem)
> +{
> + unsigned long i = 0;
> + int res = 0;
> +
> + if ( mem->nr_banks == 0 )
> + return -ENOENT;
> +
> + /*
> + * For each shared memory region, a range is exposed under
> + * the /reserved-memory node as a child node. Each range sub-node is
> + * named xen-shmem@<address>.
> + */
> + dt_dprintk("Create xen-shmem node\n");
> +
> + for ( ; i < mem->nr_banks; i++ )
> + {
> + uint64_t start = mem->bank[i].start;
> + uint64_t size = mem->bank[i].size;
> + uint8_t shm_id = mem->bank[i].shm_id;
> + /* Placeholder for xen-shmem@ + a 64-bit number + \0 */
> + char buf[27];
> + const char compat[] = "xen,shared-memory-v1";
> + __be32 reg[4];
> + __be32 *cells;
> + unsigned int len = (addrcells + sizecells) * sizeof(__be32);
> +
> + snprintf(buf, sizeof(buf), "xen-shmem@%"PRIx64, mem->bank[i].start);
> + res = fdt_begin_node(fdt, buf);
> + if ( res )
> + return res;
> +
> + res = fdt_property(fdt, "compatible", compat, sizeof(compat));
> + if ( res )
> + return res;
> +
> + cells = reg;
> + dt_child_set_range(&cells, addrcells, sizecells, start, size);
> +
> + res = fdt_property(fdt, "reg", reg, len);
> + if ( res )
> + return res;
> +
> + dt_dprintk("Shared memory bank %lu: %#"PRIx64"->%#"PRIx64"\n",
> + i, start, start + size);
> +
> + res = fdt_property_cell(fdt, "xen,id", shm_id);
> + if ( res )
> + return res;
> +
> + res = fdt_end_node(fdt);
> + if ( res )
> + return res;
> + }
> +
> + return res;
> +}
> +#else
> +static int __init make_shm_memory_node(const struct domain *d,
> + void *fdt,
> + int addrcells, int sizecells,
> + struct meminfo *mem)
> +{
> + ASSERT_UNREACHABLE();
> +}
> +#endif
> +
> +static int __init make_resv_memory_node(const struct domain *d,
> + void *fdt,
> + int addrcells, int sizecells,
> + struct meminfo *mem)
> +{
> + int res = 0;
> + /* Placeholder for reserved-memory\0 */
> + char resvbuf[16] = "reserved-memory";
> +
> + if ( mem == NULL )
> + /* No shared memory provided. */
> + return 0;
> +
> + dt_dprintk("Create reserved-memory node\n");
> +
> + res = fdt_begin_node(fdt, resvbuf);
> + if ( res )
> + return res;
> +
> + res = fdt_property(fdt, "ranges", NULL, 0);
> + if ( res )
> + return res;
> +
> + res = fdt_property_cell(fdt, "#address-cells", addrcells);
> + if ( res )
> + return res;
> +
> + res = fdt_property_cell(fdt, "#size-cells", sizecells);
> + if ( res )
> + return res;
> +
> + res = make_shm_memory_node(d, fdt, addrcells, sizecells, mem);
> + if ( res )
> + return res;
> +
> + res = fdt_end_node(fdt);
> +
> + return res;
> +}
> +
> static int __init add_ext_regions(unsigned long s, unsigned long e, void *data)
> {
> struct meminfo *ext_regions = data;
> @@ -3041,6 +3180,11 @@ static int __init prepare_dtb_domU(struct domain *d, struct kernel_info *kinfo)
> if ( ret )
> goto err;
>
> + ret = make_resv_memory_node(d, kinfo->fdt, addrcells, sizecells,
> + d->arch.shm_mem);
> + if ( ret )
> + goto err;
> +
> /*
> * domain_handle_dtb_bootmodule has to be called before the rest of
> * the device tree is generated because it depends on the value of
> diff --git a/xen/arch/arm/include/asm/domain.h b/xen/arch/arm/include/asm/domain.h
> index ed63c2b6f9..d0d1e12cfe 100644
> --- a/xen/arch/arm/include/asm/domain.h
> +++ b/xen/arch/arm/include/asm/domain.h
> @@ -104,6 +104,7 @@ struct arch_domain
> #endif
>
> bool directmap;
> + struct meminfo *shm_mem;
> } __cacheline_aligned;
>
> struct arch_vcpu
> diff --git a/xen/arch/arm/include/asm/setup.h b/xen/arch/arm/include/asm/setup.h
> index 38e02ced36..b5909acf68 100644
> --- a/xen/arch/arm/include/asm/setup.h
> +++ b/xen/arch/arm/include/asm/setup.h
> @@ -29,6 +29,7 @@ struct membank {
> bool xen_domain; /* whether the memory bank is bound to a Xen domain. */
> #ifdef CONFIG_STATIC_SHM
> unsigned long nr_shm_domain;
> + uint8_t shm_id ; /* ID identifier of a static shared memory bank. */
> #endif
> };
>
> --
> 2.25.1
>
Hi,
On 07/05/2022 02:09, Stefano Stabellini wrote:
> On Fri, 6 May 2022, Penny Zheng wrote:
>> We expose the shared memory to the domU using the "xen,shared-memory-v1"
>> reserved-memory binding. See
>> Documentation/devicetree/bindings/reserved-memory/xen,shared-memory.txt
>> in Linux for the corresponding device tree binding.
>>
>> To save the cost of re-parsing shared memory device tree configuration when
>> creating shared memory nodes in guest device tree, this commit adds new field
>> "shm_mem" to store shm-info per domain.
>>
>> For each shared memory region, a range is exposed under
>> the /reserved-memory node as a child node. Each range sub-node is
>> named xen-shmem@<address> and has the following properties:
>> - compatible:
>> compatible = "xen,shared-memory-v1"
>> - reg:
>> the base guest physical address and size of the shared memory region
>> - xen,id:
>> a string that identifies the shared memory region.
>>
>> Signed-off-by: Penny Zheng <penny.zheng@arm.com>
>> ---
>> v2 change:
>> - using xzalloc
>> - shm_id should be uint8_t
>> - make reg a local variable
>> - add #address-cells and #size-cells properties
>> - fix alignment
>> ---
>> xen/arch/arm/domain_build.c | 144 ++++++++++++++++++++++++++++++
>> xen/arch/arm/include/asm/domain.h | 1 +
>> xen/arch/arm/include/asm/setup.h | 1 +
>> 3 files changed, 146 insertions(+)
>>
>> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
>> index 8d299a3616..f08606d2c0 100644
>> --- a/xen/arch/arm/domain_build.c
>> +++ b/xen/arch/arm/domain_build.c
>> @@ -894,6 +894,26 @@ static int __init allocate_shared_memory(struct domain *d,
>> return ret;
>> }
>>
>> +static int __init append_shm_bank_to_domain(struct domain *d,
>> + paddr_t start, paddr_t size,
>> + u32 shm_id)
>> +{
>> + /* Allocate memory at first insertion. */
>> + if ( d->arch.shm_mem == NULL )
>> + {
>> + d->arch.shm_mem = xzalloc(struct meminfo);
>> + if ( d->arch.shm_mem == NULL )
>> + return -ENOMEM;
>> + }
>> +
>> + d->arch.shm_mem->bank[d->arch.shm_mem->nr_banks].start = start;
>> + d->arch.shm_mem->bank[d->arch.shm_mem->nr_banks].size = size;
>> + d->arch.shm_mem->bank[d->arch.shm_mem->nr_banks].shm_id = shm_id;
>> + d->arch.shm_mem->nr_banks++;
bank[] is a fixed size array. So we should check we don't overflow.
>> +
>> + return 0;
>> +}
>
> Can we call xfree(d->arch.shm_mem) at domain destruction?
>
> Even better, we might be able to call it earlier, soon after the
> make_resv_memory_node() call because we don't need it any longer after
> that?
If this is only used during domain build, then the field should move to
kernel_info. With that, there will also be no concern on whether we need
to allocate the structure or not.
Cheers,
--
Julien Grall
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