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x86/hyperv: Remove BUG_ON() for kmap_local_page()

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The commit 154fb14df7 ("x86/hyperv: Replace kmap() with
kmap_local_page()") keeps the BUG_ON() to check if kmap_local_page()
fails.

But in fact, kmap_local_page() always returns a valid kernel address
and won't return NULL here. It will BUG on its own if it fails. [1]

So directly use memcpy_to_page() which creates local mapping to copy.

[1]: https://lore.kernel.org/lkml/YztFEyUA48et0yTt@iweiny-mobl/

Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20221020083820.2341088-1-zhao1.liu@linux.intel.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This commit is contained in:
Zhao Liu 2022-10-20 16:38:20 +08:00 committed by Wei Liu
parent 247f34f7b8
commit 03b9a6e18d
1 changed files with 3 additions and 5 deletions
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8
arch/x86/hyperv/hv_init.c
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@ -444,7 +444,7 @@ void __init hyperv_init(void)
if (hv_root_partition) {
struct page *pg;
void *src, *dst;
void *src;
/*
* For the root partition, the hypervisor will set up its
@ -459,13 +459,11 @@ void __init hyperv_init(void)
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
pg = vmalloc_to_page(hv_hypercall_pg);
dst = kmap_local_page(pg);
src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE,
MEMREMAP_WB);
BUG_ON(!(src && dst));
memcpy(dst, src, HV_HYP_PAGE_SIZE);
BUG_ON(!src);
memcpy_to_page(pg, 0, src, HV_HYP_PAGE_SIZE);
memunmap(src);
kunmap_local(dst);
} else {
hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);