[PATCH v4 06/14] virt: gunyah: Add sysfs nodes

Elliot Berman
2022-09-28T19:58:37Z

Add /sys/hypervisor support when detecting that Linux is running in a
Gunyah environment. Export the version of Gunyah which is reported via
the hyp_identify hypercall.

Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
---
.../ABI/testing/sysfs-hypervisor-gunyah | 15 ++++
MAINTAINERS | 1 +
drivers/virt/Makefile | 1 +
drivers/virt/gunyah/Makefile | 2 +
drivers/virt/gunyah/sysfs.c | 71 +++++++++++++++++++
5 files changed, 90 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-hypervisor-gunyah
create mode 100644 drivers/virt/gunyah/Makefile
create mode 100644 drivers/virt/gunyah/sysfs.c

diff --git a/Documentation/ABI/testing/sysfs-hypervisor-gunyah b/Documentation/ABI/testing/sysfs-hypervisor-gunyah
new file mode 100644
index 000000000000..7d74e74e9edd
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-hypervisor-gunyah
@@ -0,0 +1,15 @@
+What: /sys/hypervisor/gunyah/api
+Date: October 2022
+KernelVersion: 6.1
+Contact: linux-arm-msm@vger.kernel.org
+Description: If running under Gunyah:
+ The Gunyah API version.
+
+What: /sys/hypervisor/gunyah/variant
+Date: October 2022
+KernelVersion: 6.1
+Contact: linux-arm-msm@vger.kernel.org
+Description: If running under Gunyah:
+ Reports the build variant of Gunyah:
+ The open source build of Gunyah will report "81".
+ The Qualcomm build of Gunyah will report "72".
diff --git a/MAINTAINERS b/MAINTAINERS
index feafac12db35..a26e67ef36b4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8885,6 +8885,7 @@ M: Elliot Berman <quic_eberman@quicinc.com>
M: Murali Nalajala <quic_mnalajal@quicinc.com>
L: linux-arm-msm@vger.kernel.org
S: Supported
+F: Documentation/ABI/testing/sysfs-hypervisor-gunyah
F: Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml
F: Documentation/virt/gunyah/
F: arch/arm64/gunyah/
diff --git a/drivers/virt/Makefile b/drivers/virt/Makefile
index 093674e05c40..10b87f934730 100644
--- a/drivers/virt/Makefile
+++ b/drivers/virt/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_NITRO_ENCLAVES) += nitro_enclaves/
obj-$(CONFIG_ACRN_HSM) += acrn/
obj-$(CONFIG_EFI_SECRET) += coco/efi_secret/
obj-$(CONFIG_SEV_GUEST) += coco/sev-guest/
+obj-$(CONFIG_GUNYAH) += gunyah/
diff --git a/drivers/virt/gunyah/Makefile b/drivers/virt/gunyah/Makefile
new file mode 100644
index 000000000000..e15f16c17142
--- /dev/null
+++ b/drivers/virt/gunyah/Makefile
@@ -0,0 +1,2 @@
+gunyah-y += sysfs.o
+obj-$(CONFIG_GUNYAH) += gunyah.o
diff --git a/drivers/virt/gunyah/sysfs.c b/drivers/virt/gunyah/sysfs.c
new file mode 100644
index 000000000000..ec11510cbece
--- /dev/null
+++ b/drivers/virt/gunyah/sysfs.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#define pr_fmt(fmt) "gunyah: " fmt
+
+#include <linux/kobject.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/init.h>
+#include <asm-generic/gunyah.h>
+
+static struct gh_hypercall_hyp_identify_resp gunyah_api;
+
+static ssize_t api_show(struct kobject *kobj, struct kobj_attribute *attr, char *buffer)
+{
+ return sysfs_emit(buffer, "%d\n", (int)GH_API_INFO_API_VERSION(gunyah_api.api_info));
+}
+static struct kobj_attribute api_attr = __ATTR_RO(api);
+
+static ssize_t variant_show(struct kobject *kobj, struct kobj_attribute *attr, char *buffer)
+{
+ return sysfs_emit(buffer, "%d\n", (int)GH_API_INFO_VARIANT(gunyah_api.api_info));
+}
+static struct kobj_attribute variant_attr = __ATTR_RO(variant);
+
+static struct attribute *gunyah_attrs[] = {
+ &api_attr.attr,
+ &variant_attr.attr,
+ NULL
+};
+
+static const struct attribute_group gunyah_group = {
+ .name = "gunyah",
+ .attrs = gunyah_attrs,
+};
+
+static int __init gunyah_init(void)
+{
+ u32 uid[4];
+
+ gh_hypercall_get_uid(uid);
+
+ if (!(gh_uid_matches(GUNYAH, uid) || gh_uid_matches(QC_HYP, uid)))
+ return 0;
+
+ gh_hypercall_hyp_identify(&gunyah_api);
+
+ if (GH_API_INFO_API_VERSION(gunyah_api.api_info) != 1) {
+ pr_warn("Unrecognized gunyah version: %llu. Currently supported: 1\n",
+ GH_API_INFO_API_VERSION(gunyah_api.api_info));
+ return 0;
+ }
+
+ pr_notice("Running under Gunyah hypervisor %llx/v%lld\n",
+ GH_API_INFO_VARIANT(gunyah_api.api_info),
+ GH_API_INFO_API_VERSION(gunyah_api.api_info));
+
+ return sysfs_create_group(hypervisor_kobj, &gunyah_group);
+}
+module_init(gunyah_init);
+
+static void __exit gunyah_exit(void)
+{
+ sysfs_remove_group(hypervisor_kobj, &gunyah_group);
+}
+module_exit(gunyah_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Gunyah Hypervisor Driver");
--
2.25.1