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powerpc/64s/radix: Fix radix_kvm_prefetch_workaround paca access of not possible CPU

PATCH Applied Nicholas Piggin 2 participants 2 messages Jun 12, 2018 – Jun 23, 2018 PowerPC

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Nicholas Piggin

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PATCH 1/1 powerpc/64s/radix: Fix radix_kvm_prefetch_workaround paca access of not possible CPU

If possible CPUs are limited (e.g., by kexec), then the kvm prefetch workaround function can access the paca pointer for a !possible CPU.

Fixes d2e60075a3d44 ("powerpc/64: Use array of paca pointers and allocate pacas individually")
Cc [email protected]
Reported-by Pridhiviraj Paidipeddi <[email protected]>
Tested-by Pridhiviraj Paidipeddi <[email protected]>
Signed-off-by Nicholas Piggin <[email protected]>

---
[kdump still seems to have a problem upstream, but this solves one crash]

 arch/powerpc/mm/tlb-radix.c | 2 ++
 1 file changed, 2 insertions(+)
arch/powerpc/mm/tlb-radix.c +2 -0
index 67a6e86d3e7e..06ea845d8033 100644
@@ -1043,6 +1043,8 @@ extern void radix_kvm_prefetch_workaround(struct mm_struct *mm)
 		for (; sib <= cpu_last_thread_sibling(cpu) && !flush; sib++) {
 			if (sib == cpu)
 				continue;
+			if (!cpu_possible(sib))
+				continue;
 			if (paca_ptrs[sib]->kvm_hstate.kvm_vcpu)
 				flush = true;
 		}
Signature · 1 line
2.17.0
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Quoted 8 lines · Nicholas Piggin

If possible CPUs are limited (e.g., by kexec), then the kvm prefetch workaround function can access the paca pointer for a !possible CPU.

Fixes d2e60075a3d44 ("powerpc/64: Use array of paca pointers and allocate pacas individually")
Cc [email protected]
Reported-by Pridhiviraj Paidipeddi <[email protected]>
Tested-by Pridhiviraj Paidipeddi <[email protected]>
Signed-off-by Nicholas Piggin <[email protected]>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/758380b8155f69b4e2f77f27562f8a

cheers