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authorMichael Kelley <mikelley@microsoft.com>2021-06-03 00:36:44 +0300
committerWei Liu <wei.liu@kernel.org>2021-06-05 13:22:34 +0300
commita4d7e8ae4a541557d7a2c815835b786c18c3613c (patch)
treebf4fa1616a306ed14f80e85e0621a2f00a07e0bc /drivers/hv/hv_common.c
parent9de6655cc5a6a1febc514465c87c24a0e96d8dba (diff)
downloadlinux-a4d7e8ae4a541557d7a2c815835b786c18c3613c.tar.xz
Drivers: hv: Move Hyper-V extended capability check to arch neutral code
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@microsoft.com> Reviewed-by: Sunil Muthuswamy <sunilmut@microsoft.com> Link: https://lore.kernel.org/r/1622669804-2016-1-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
Diffstat (limited to 'drivers/hv/hv_common.c')
-rw-r--r--drivers/hv/hv_common.c66
1 files changed, 66 insertions, 0 deletions
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
new file mode 100644
index 000000000000..f0053c786891
--- /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@microsoft.com>
+ */
+
+#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);