linux-kernel - [PATCH v3 2/5] x86: hv: hv_init.c: Add functions to allocate/deallocate page for Hyper-V

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Date:   Tue, 18 Jun 2019 06:13:08 +0000
From:   Maya Nakamura <m.maya.nakamura@...il.com>
To:     mikelley@...rosoft.com, kys@...rosoft.com, haiyangz@...rosoft.com,
        sthemmin@...rosoft.com, sashal@...nel.org
Cc:     x86@...nel.org, linux-hyperv@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 2/5] x86: hv: hv_init.c: Add functions to
 allocate/deallocate page for Hyper-V

Introduce two new functions, hv_alloc_hyperv_page() and
hv_free_hyperv_page(), to allocate/deallocate memory with the size and
alignment that Hyper-V expects as a page. Although currently they are
not used, they are ready to be used to allocate/deallocate memory on x86
when their ARM64 counterparts are implemented, keeping symmetry between
architectures with potentially different guest page sizes.

Link: https://lore.kernel.org/lkml/87muindr9c.fsf@vitty.brq.redhat.com/
Signed-off-by: Maya Nakamura <m.maya.nakamura@...il.com>
Reviewed-by: Michael Kelley <mikelley@...rosoft.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/hyperv/hv_init.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 0e033ef11a9f..e8960a83add7 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -37,6 +37,20 @@ EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
 u32 hv_max_vp_index;
 EXPORT_SYMBOL_GPL(hv_max_vp_index);
 
+void *hv_alloc_hyperv_page(void)
+{
+	BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE);
+
+	return (void *)__get_free_page(GFP_KERNEL);
+}
+EXPORT_SYMBOL_GPL(hv_alloc_hyperv_page);
+
+void hv_free_hyperv_page(unsigned long addr)
+{
+	free_page(addr);
+}
+EXPORT_SYMBOL_GPL(hv_free_hyperv_page);
+
 static int hv_cpu_init(unsigned int cpu)
 {
 	u64 msr_vp_index;
-- 
2.17.1