[PATCH V3 1/4] arm/io: Use separate memory allocation for mmio handlers

From: Shanker Donthineni
Date: Wed Jul 20 2016 - 09:54:25 EST


The number of mmio handlers are limited to a compile time macro
MAX_IO_HANDLER which is 16. This number is not at all sufficient
to support per CPU distributor regions. Either it needs to be
increased to a bigger number, at least CONFIG_NR_CPUS+16, or
allocate a separate memory for mmio handlers dynamically during
domain build.

This patch uses the dynamic allocation strategy to reduce memory
footprint for 'struct domain' instead of static allocation.

Signed-off-by: Shanker Donthineni <shankerd@xxxxxxxxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>
---
xen/arch/arm/domain.c | 6 ++++--
xen/arch/arm/io.c | 13 +++++++++++--
xen/include/asm-arm/mmio.h | 7 +++++--
3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 61fc08e..0170cee 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -546,7 +546,7 @@ void vcpu_destroy(struct vcpu *v)
int arch_domain_create(struct domain *d, unsigned int domcr_flags,
struct xen_arch_domainconfig *config)
{
- int rc;
+ int rc, count;

d->arch.relmem = RELMEM_not_started;

@@ -569,7 +569,8 @@ int arch_domain_create(struct domain *d, unsigned int domcr_flags,
share_xen_page_with_guest(
virt_to_page(d->shared_info), d, XENSHARE_writable);

- if ( (rc = domain_io_init(d)) != 0 )
+ count = MAX_IO_HANDLER;
+ if ( (rc = domain_io_init(d, count)) != 0 )
goto fail;

if ( (rc = p2m_alloc_table(d)) != 0 )
@@ -663,6 +664,7 @@ void arch_domain_destroy(struct domain *d)
free_xenheap_pages(d->arch.efi_acpi_table,
get_order_from_bytes(d->arch.efi_acpi_len));
#endif
+ domain_io_free(d);
}

void arch_domain_shutdown(struct domain *d)
diff --git a/xen/arch/arm/io.c b/xen/arch/arm/io.c
index 5a96836..40330f0 100644
--- a/xen/arch/arm/io.c
+++ b/xen/arch/arm/io.c
@@ -118,7 +118,7 @@ void register_mmio_handler(struct domain *d,
struct vmmio *vmmio = &d->arch.vmmio;
struct mmio_handler *handler;

- BUG_ON(vmmio->num_entries >= MAX_IO_HANDLER);
+ BUG_ON(vmmio->num_entries >= vmmio->max_num_entries);

write_lock(&vmmio->lock);

@@ -134,14 +134,23 @@ void register_mmio_handler(struct domain *d,
write_unlock(&vmmio->lock);
}

-int domain_io_init(struct domain *d)
+int domain_io_init(struct domain *d, int max_count)
{
rwlock_init(&d->arch.vmmio.lock);
d->arch.vmmio.num_entries = 0;
+ d->arch.vmmio.max_num_entries = max_count;
+ d->arch.vmmio.handlers = xzalloc_array(struct mmio_handler, max_count);
+ if ( !d->arch.vmmio.handlers )
+ return -ENOMEM;

return 0;
}

+void domain_io_free(struct domain *d)
+{
+ xfree(d->arch.vmmio.handlers);
+}
+
/*
* Local variables:
* mode: C
diff --git a/xen/include/asm-arm/mmio.h b/xen/include/asm-arm/mmio.h
index 32f10f2..c620eed 100644
--- a/xen/include/asm-arm/mmio.h
+++ b/xen/include/asm-arm/mmio.h
@@ -52,15 +52,18 @@ struct mmio_handler {

struct vmmio {
int num_entries;
+ int max_num_entries;
rwlock_t lock;
- struct mmio_handler handlers[MAX_IO_HANDLER];
+ struct mmio_handler *handlers;
};

extern int handle_mmio(mmio_info_t *info);
void register_mmio_handler(struct domain *d,
const struct mmio_handler_ops *ops,
paddr_t addr, paddr_t size, void *priv);
-int domain_io_init(struct domain *d);
+int domain_io_init(struct domain *d, int max_count);
+void domain_io_free(struct domain *d);
+

#endif /* __ASM_ARM_MMIO_H__ */

--
Qualcomm Datacenter Technologies, Inc. on behalf of the Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.