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x86/mm: fix poking_init() for Xen PV guests

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Commit 3f4c8211d9 ("x86/mm: Use mm_alloc() in poking_init()") broke
the kernel for running as Xen PV guest.

It seems as if the new address space is never activated before being
used, resulting in Xen rejecting to accept the new CR3 value (the PGD
isn't pinned).

Fix that by adding the now missing call of paravirt_arch_dup_mmap() to
poking_init(). That call was previously done by dup_mm()->dup_mmap() and
it is a NOP for all cases but for Xen PV, where it is just doing the
pinning of the PGD.

Fixes: 3f4c8211d9 ("x86/mm: Use mm_alloc() in poking_init()")
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230109150922.10578-1-jgross@suse.com
This commit is contained in:
Juergen Gross 2023-01-09 16:09:22 +01:00 committed by Peter Zijlstra
parent 2a81160d29
commit 26ce6ec364
1 changed files with 4 additions and 0 deletions
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4
arch/x86/mm/init.c
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@ -26,6 +26,7 @@
#include <asm/pti.h>
#include <asm/text-patching.h>
#include <asm/memtype.h>
#include <asm/paravirt.h>
/*
* We need to define the tracepoints somewhere, and tlb.c
@ -804,6 +805,9 @@ void __init poking_init(void)
poking_mm = mm_alloc();
BUG_ON(!poking_mm);
/* Xen PV guests need the PGD to be pinned. */
paravirt_arch_dup_mmap(NULL, poking_mm);
/*
* Randomize the poking address, but make sure that the following page
* will be mapped at the same PMD. We need 2 pages, so find space for 3,