From: Vitaly Kuznetsov <vkuznets@redhat.com> Sent: Tuesday, March 2, 2021 4:57 AM
Michael Kelley [off-list ref] writes:
quoted
The Hyper-V page allocator functions are implemented in an architecture
neutral way. Move them into the architecture neutral VMbus module so
a separate implementation for ARM64 is not needed.
No functional change.
Signed-off-by: Michael Kelley <redacted>
Reviewed-by: Boqun Feng <redacted>
---
arch/x86/hyperv/hv_init.c | 22 ----------------------
arch/x86/include/asm/mshyperv.h | 5 -----
drivers/hv/hv.c | 36 ++++++++++++++++++++++++++++++++++++
include/asm-generic/mshyperv.h | 4 ++++
4 files changed, 40 insertions(+), 27 deletions(-)
[snip]
quoted
/*
+ * 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.
+ */
+
+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);
PAGE_SIZE and HV_HYP_PAGE_SIZE are known compile-time and in case this
won't change in the future we can probably write this as
#if PAGE_SIZE == HV_HYP_PAGE_SIZE
return (void *)__get_free_page(GFP_KERNEL);
#else
return kmalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
#endif
(not sure if the output is going to be any different with e.g. gcc's '-O2')
I looked at the generated code, and the compiler does the right
thing on both x86/x64 and on ARM64. I'd rather leave the code
as is so that both legs of the 'if' statement get checked by the
compiler regardless of whether PAGE_SIZE == HV_HYP_PAGE_SIZE.
Michael
quoted
+}
+
+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);
+}
+
+void hv_free_hyperv_page(unsigned long addr)
+{
+ if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
+ free_page(addr);
+ else
+ kfree((void *)addr);
+}
+
+/*