linux-kernel - [PATCH v7 04/10] arm64: hyperv: Add memory alloc/free functions for Hyper-V size pages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1598287583-71762-5-git-send-email-mikelley@microsoft.com>
Date:   Mon, 24 Aug 2020 09:46:17 -0700
From:   Michael Kelley <mikelley@...rosoft.com>
To:     will@...nel.org, ardb@...nel.org, arnd@...db.de,
        catalin.marinas@....com, mark.rutland@....com, maz@...nel.org,
        linux-arm-kernel@...ts.infradead.org, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org,
        linux-efi@...r.kernel.org, linux-arch@...r.kernel.org,
        wei.liu@...nel.org, vkuznets@...hat.com, kys@...rosoft.com
Cc:     mikelley@...rosoft.com, sunilmut@...rosoft.com,
        boqun.feng@...il.com
Subject: [PATCH v7 04/10] arm64: hyperv: Add memory alloc/free functions for Hyper-V size pages

Add ARM64-specific code to allocate memory with HV_HYP_PAGE_SIZE
size and alignment. These are for use when pages need to be shared
with Hyper-V. Separate functions are needed as the page size used
by Hyper-V may not be the same as the guest page size.

This code is built only when CONFIG_HYPERV is enabled.

Signed-off-by: Michael Kelley <mikelley@...rosoft.com>
---
 arch/arm64/hyperv/hv_core.c    | 43 ++++++++++++++++++++++++++++++++++++++++++
 include/asm-generic/mshyperv.h |  5 +++++
 2 files changed, 48 insertions(+)

diff --git a/arch/arm64/hyperv/hv_core.c b/arch/arm64/hyperv/hv_core.c
index 9b35011..14e41b7 100644
--- a/arch/arm64/hyperv/hv_core.c
+++ b/arch/arm64/hyperv/hv_core.c
@@ -24,6 +24,49 @@
 
 
 /*
+ * Functions for allocating and freeing memory with size and
+ * alignment HV_HYP_PAGE_SIZE. These functions are needed because
+ * the guest page size may not be the same as the Hyper-V page
+ * size. We depend upon kmalloc() aligning power-of-two size
+ * allocations to the allocation size boundary, so that the
+ * allocated memory appears to Hyper-V as a page of the size
+ * it expects.
+ *
+ * These functions are used by arm64 specific code as well as
+ * arch independent Hyper-V drivers.
+ */
+
+void *hv_alloc_hyperv_page(void)
+{
+	BUILD_BUG_ON(PAGE_SIZE <  HV_HYP_PAGE_SIZE);
+
+	if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
+		return (void *)__get_free_page(GFP_KERNEL);
+	else
+		return kmalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
+}
+EXPORT_SYMBOL_GPL(hv_alloc_hyperv_page);
+
+void *hv_alloc_hyperv_zeroed_page(void)
+{
+	if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
+		return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+	else
+		return kzalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
+}
+EXPORT_SYMBOL_GPL(hv_alloc_hyperv_zeroed_page);
+
+void hv_free_hyperv_page(unsigned long addr)
+{
+	if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
+		free_page(addr);
+	else
+		kfree((void *)addr);
+}
+EXPORT_SYMBOL_GPL(hv_free_hyperv_page);
+
+
+/*
  * hv_do_hypercall- Invoke the specified hypercall
  */
 u64 hv_do_hypercall(u64 control, void *input, void *output)
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index c577996..d345a59 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -101,6 +101,11 @@ static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
 
 extern int vmbus_interrupt;
 
+void *hv_alloc_hyperv_page(void);
+void *hv_alloc_hyperv_zeroed_page(void);
+void hv_free_hyperv_page(unsigned long addr);
+
+
 #if IS_ENABLED(CONFIG_HYPERV)
 /*
  * Hypervisor's notion of virtual processor ID is different from
-- 
1.8.3.1