[PATCH 1/1] Drivers: hv: Move Hyper-V extended capability check to arch neutral code
From: Michael Kelley
Date: Wed Jun 02 2021 - 17:37:07 EST
The extended capability query code is currently under arch/x86, but it
is architecture neutral, and is used by arch neutral code in the Hyper-V
balloon driver. Hence the balloon driver fails to build on other
architectures.
Fix by moving the ext cap code out from arch/x86. Because it is also
called from built-in architecture specific code, it can't be in a module,
so the Makefile treats as built-in even when CONFIG_HYPERV is "m". Also
drivers/Makefile is tweaked because this is the first occurrence of a
Hyper-V file that is built-in even when CONFIG_HYPERV is "m".
While here, update the hypercall status check to use the new helper
function instead of open coding. No functional change.
Signed-off-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
---
arch/x86/hyperv/hv_init.c | 47 ---------------------------------
drivers/Makefile | 2 +-
drivers/hv/Makefile | 3 +++
drivers/hv/hv_common.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 70 insertions(+), 48 deletions(-)
create mode 100644 drivers/hv/hv_common.c
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index bb0ae4b..6952e21 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -614,50 +614,3 @@ bool hv_is_isolation_supported(void)
return hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE;
}
EXPORT_SYMBOL_GPL(hv_is_isolation_supported);
-
-/* Bit mask of the extended capability to query: see HV_EXT_CAPABILITY_xxx */
-bool hv_query_ext_cap(u64 cap_query)
-{
- /*
- * The address of the 'hv_extended_cap' variable will be used as an
- * output parameter to the hypercall below and so it should be
- * compatible with 'virt_to_phys'. Which means, it's address should be
- * directly mapped. Use 'static' to keep it compatible; stack variables
- * can be virtually mapped, making them imcompatible with
- * 'virt_to_phys'.
- * Hypercall input/output addresses should also be 8-byte aligned.
- */
- static u64 hv_extended_cap __aligned(8);
- static bool hv_extended_cap_queried;
- u64 status;
-
- /*
- * Querying extended capabilities is an extended hypercall. Check if the
- * partition supports extended hypercall, first.
- */
- if (!(ms_hyperv.priv_high & HV_ENABLE_EXTENDED_HYPERCALLS))
- return false;
-
- /* Extended capabilities do not change at runtime. */
- if (hv_extended_cap_queried)
- return hv_extended_cap & cap_query;
-
- status = hv_do_hypercall(HV_EXT_CALL_QUERY_CAPABILITIES, NULL,
- &hv_extended_cap);
-
- /*
- * The query extended capabilities hypercall should not fail under
- * any normal circumstances. Avoid repeatedly making the hypercall, on
- * error.
- */
- hv_extended_cap_queried = true;
- status &= HV_HYPERCALL_RESULT_MASK;
- if (status != HV_STATUS_SUCCESS) {
- pr_err("Hyper-V: Extended query capabilities hypercall failed 0x%llx\n",
- status);
- return false;
- }
-
- return hv_extended_cap & cap_query;
-}
-EXPORT_SYMBOL_GPL(hv_query_ext_cap);
diff --git a/drivers/Makefile b/drivers/Makefile
index 5a6d613..1c2e1ac 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -161,7 +161,7 @@ obj-$(CONFIG_SOUNDWIRE) += soundwire/
# Virtualization drivers
obj-$(CONFIG_VIRT_DRIVERS) += virt/
-obj-$(CONFIG_HYPERV) += hv/
+obj-$(subst m,y,$(CONFIG_HYPERV)) += hv/
obj-$(CONFIG_PM_DEVFREQ) += devfreq/
obj-$(CONFIG_EXTCON) += extcon/
diff --git a/drivers/hv/Makefile b/drivers/hv/Makefile
index 94daf82..d76df5c 100644
--- a/drivers/hv/Makefile
+++ b/drivers/hv/Makefile
@@ -11,3 +11,6 @@ hv_vmbus-y := vmbus_drv.o \
channel_mgmt.o ring_buffer.o hv_trace.o
hv_vmbus-$(CONFIG_HYPERV_TESTING) += hv_debugfs.o
hv_utils-y := hv_util.o hv_kvp.o hv_snapshot.o hv_fcopy.o hv_utils_transport.o
+
+# Code that must be built-in
+obj-$(subst m,y,$(CONFIG_HYPERV)) += hv_common.o
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
new file mode 100644
index 0000000..f0053c7
--- /dev/null
+++ b/drivers/hv/hv_common.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Architecture neutral utility routines for interacting with
+ * Hyper-V. This file is specifically for code that must be
+ * built-in to the kernel image when CONFIG_HYPERV is set
+ * (vs. being in a module) because it is called from architecture
+ * specific code under arch/.
+ *
+ * Copyright (C) 2021, Microsoft, Inc.
+ *
+ * Author : Michael Kelley <mikelley@xxxxxxxxxxxxx>
+ */
+
+#include <linux/types.h>
+#include <linux/export.h>
+#include <linux/bitfield.h>
+#include <asm/hyperv-tlfs.h>
+#include <asm/mshyperv.h>
+
+
+/* Bit mask of the extended capability to query: see HV_EXT_CAPABILITY_xxx */
+bool hv_query_ext_cap(u64 cap_query)
+{
+ /*
+ * The address of the 'hv_extended_cap' variable will be used as an
+ * output parameter to the hypercall below and so it should be
+ * compatible with 'virt_to_phys'. Which means, it's address should be
+ * directly mapped. Use 'static' to keep it compatible; stack variables
+ * can be virtually mapped, making them imcompatible with
+ * 'virt_to_phys'.
+ * Hypercall input/output addresses should also be 8-byte aligned.
+ */
+ static u64 hv_extended_cap __aligned(8);
+ static bool hv_extended_cap_queried;
+ u64 status;
+
+ /*
+ * Querying extended capabilities is an extended hypercall. Check if the
+ * partition supports extended hypercall, first.
+ */
+ if (!(ms_hyperv.priv_high & HV_ENABLE_EXTENDED_HYPERCALLS))
+ return false;
+
+ /* Extended capabilities do not change at runtime. */
+ if (hv_extended_cap_queried)
+ return hv_extended_cap & cap_query;
+
+ status = hv_do_hypercall(HV_EXT_CALL_QUERY_CAPABILITIES, NULL,
+ &hv_extended_cap);
+
+ /*
+ * The query extended capabilities hypercall should not fail under
+ * any normal circumstances. Avoid repeatedly making the hypercall, on
+ * error.
+ */
+ hv_extended_cap_queried = true;
+ if (!hv_result_success(status)) {
+ pr_err("Hyper-V: Extended query capabilities hypercall failed 0x%llx\n",
+ status);
+ return false;
+ }
+
+ return hv_extended_cap & cap_query;
+}
+EXPORT_SYMBOL_GPL(hv_query_ext_cap);
--
1.8.3.1