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authorOleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>2021-12-09 23:05:35 +0300
committerJuergen Gross <jgross@suse.com>2022-01-06 11:53:41 +0300
commitb2371587fe0c02657db89b67b72efc581bd3f7a0 (patch)
treed2b161445de40654e776a5b1c412293690a139f2 /arch/arm/xen
parentd1a928eac72962b562162c25baf45ce147e27247 (diff)
downloadlinux-b2371587fe0c02657db89b67b72efc581bd3f7a0.tar.xz
arm/xen: Read extended regions from DT and init Xen resource
This patch implements arch_xen_unpopulated_init() on Arm where the extended regions (if any) are gathered from DT and inserted into specific Xen resource to be used as unused address space for Xen scratch pages by unpopulated-alloc code. The extended region (safe range) is a region of guest physical address space which is unused and could be safely used to create grant/foreign mappings instead of wasting real RAM pages from the domain memory for establishing these mappings. The extended regions are chosen by the hypervisor at the domain creation time and advertised to it via "reg" property under hypervisor node in the guest device-tree. As region 0 is reserved for grant table space (always present), the indexes for extended regions are 1...N. If arch_xen_unpopulated_init() fails for some reason the default behaviour will be restored (allocate xenballooned pages). This patch also removes XEN_UNPOPULATED_ALLOC dependency on x86. Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/1639080336-26573-6-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'arch/arm/xen')
-rw-r--r--arch/arm/xen/enlighten.c106
1 files changed, 106 insertions, 0 deletions
diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 49bb6757d031..ec5b082f3de6 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -62,6 +62,7 @@ static __read_mostly unsigned int xen_events_irq;
static __read_mostly phys_addr_t xen_grant_frames;
#define GRANT_TABLE_INDEX 0
+#define EXT_REGION_INDEX 1
uint32_t xen_start_flags;
EXPORT_SYMBOL(xen_start_flags);
@@ -303,6 +304,111 @@ static void __init xen_acpi_guest_init(void)
#endif
}
+#ifdef CONFIG_XEN_UNPOPULATED_ALLOC
+/*
+ * A type-less specific Xen resource which contains extended regions
+ * (unused regions of guest physical address space provided by the hypervisor).
+ */
+static struct resource xen_resource = {
+ .name = "Xen unused space",
+};
+
+int __init arch_xen_unpopulated_init(struct resource **res)
+{
+ struct device_node *np;
+ struct resource *regs, *tmp_res;
+ uint64_t min_gpaddr = -1, max_gpaddr = 0;
+ unsigned int i, nr_reg = 0;
+ int rc;
+
+ if (!xen_domain())
+ return -ENODEV;
+
+ if (!acpi_disabled)
+ return -ENODEV;
+
+ np = of_find_compatible_node(NULL, NULL, "xen,xen");
+ if (WARN_ON(!np))
+ return -ENODEV;
+
+ /* Skip region 0 which is reserved for grant table space */
+ while (of_get_address(np, nr_reg + EXT_REGION_INDEX, NULL, NULL))
+ nr_reg++;
+
+ if (!nr_reg) {
+ pr_err("No extended regions are found\n");
+ return -EINVAL;
+ }
+
+ regs = kcalloc(nr_reg, sizeof(*regs), GFP_KERNEL);
+ if (!regs)
+ return -ENOMEM;
+
+ /*
+ * Create resource from extended regions provided by the hypervisor to be
+ * used as unused address space for Xen scratch pages.
+ */
+ for (i = 0; i < nr_reg; i++) {
+ rc = of_address_to_resource(np, i + EXT_REGION_INDEX, &regs[i]);
+ if (rc)
+ goto err;
+
+ if (max_gpaddr < regs[i].end)
+ max_gpaddr = regs[i].end;
+ if (min_gpaddr > regs[i].start)
+ min_gpaddr = regs[i].start;
+ }
+
+ xen_resource.start = min_gpaddr;
+ xen_resource.end = max_gpaddr;
+
+ /*
+ * Mark holes between extended regions as unavailable. The rest of that
+ * address space will be available for the allocation.
+ */
+ for (i = 1; i < nr_reg; i++) {
+ resource_size_t start, end;
+
+ /* There is an overlap between regions */
+ if (regs[i - 1].end + 1 > regs[i].start) {
+ rc = -EINVAL;
+ goto err;
+ }
+
+ /* There is no hole between regions */
+ if (regs[i - 1].end + 1 == regs[i].start)
+ continue;
+
+ start = regs[i - 1].end + 1;
+ end = regs[i].start - 1;
+
+ tmp_res = kzalloc(sizeof(*tmp_res), GFP_KERNEL);
+ if (!tmp_res) {
+ rc = -ENOMEM;
+ goto err;
+ }
+
+ tmp_res->name = "Unavailable space";
+ tmp_res->start = start;
+ tmp_res->end = end;
+
+ rc = insert_resource(&xen_resource, tmp_res);
+ if (rc) {
+ pr_err("Cannot insert resource %pR (%d)\n", tmp_res, rc);
+ kfree(tmp_res);
+ goto err;
+ }
+ }
+
+ *res = &xen_resource;
+
+err:
+ kfree(regs);
+
+ return rc;
+}
+#endif
+
static void __init xen_dt_guest_init(void)
{
struct device_node *xen_node;