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powerpc/book3s64/keys/kuap: Reset AMR/IAMR values on kexec

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As we kexec across kernels that use AMR/IAMR for different purposes
we need to ensure that new kernels get kexec'd with a reset value
of AMR/IAMR. For ex: the new kernel can use key 0 for kernel mapping and the old
AMR value prevents access to key 0.

This patch also removes reset if IAMR and AMOR in kexec_sequence. Reset of AMOR
is not needed and the IAMR reset is partial (it doesn't do the reset
on secondary cpus) and is redundant with this patch.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200709032946.881753-19-aneesh.kumar@linux.ibm.com
This commit is contained in:
Aneesh Kumar K.V 2020-07-09 08:59:41 +05:30 committed by Michael Ellerman
parent 7cdd3745f2
commit 000a42b35a
5 changed files with 40 additions and 14 deletions
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23
arch/powerpc/include/asm/book3s/64/kexec.h Normal file
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@ -0,0 +1,23 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_POWERPC_BOOK3S_64_KEXEC_H_
#define _ASM_POWERPC_BOOK3S_64_KEXEC_H_
#define reset_sprs reset_sprs
static inline void reset_sprs(void)
{
if (cpu_has_feature(CPU_FTR_ARCH_206)) {
mtspr(SPRN_AMR, 0);
mtspr(SPRN_UAMOR, 0);
}
if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
mtspr(SPRN_IAMR, 0);
}
/* Do we need isync()? We are going via a kexec reset */
isync();
}
#endif

12
arch/powerpc/include/asm/kexec.h
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@ -150,6 +150,18 @@ static inline void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *))
}
#endif /* CONFIG_KEXEC_CORE */
#ifdef CONFIG_PPC_BOOK3S_64
#include <asm/book3s/64/kexec.h>
#endif
#ifndef reset_sprs
#define reset_sprs reset_sprs
static inline void reset_sprs(void)
{
}
#endif
#endif /* ! __ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_KEXEC_H */

14
arch/powerpc/kernel/misc_64.S
View File

@ -413,20 +413,6 @@ _GLOBAL(kexec_sequence)
li r0,0
std r0,16(r1)
BEGIN_FTR_SECTION
/*
* This is the best time to turn AMR/IAMR off.
* key 0 is used in radix for supervisor<->user
* protection, but on hash key 0 is reserved
* ideally we want to enter with a clean state.
* NOTE, we rely on r0 being 0 from above.
*/
mtspr SPRN_IAMR,r0
BEGIN_FTR_SECTION_NESTED(42)
mtspr SPRN_AMOR,r0
END_FTR_SECTION_NESTED_IFSET(CPU_FTR_HVMODE, 42)
END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
/* save regs for local vars on new stack.
* yes, we won't go back, but ...
*/

2
arch/powerpc/kexec/core_64.c
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@ -152,6 +152,8 @@ static void kexec_smp_down(void *arg)
if (ppc_md.kexec_cpu_down)
ppc_md.kexec_cpu_down(0, 1);
reset_sprs();
kexec_smp_wait();
/* NOTREACHED */
}

3
arch/powerpc/mm/book3s64/pgtable.c
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@ -15,6 +15,7 @@
#include <asm/powernv.h>
#include <asm/firmware.h>
#include <asm/ultravisor.h>
#include <asm/kexec.h>
#include <mm/mmu_decl.h>
#include <trace/events/thp.h>
@ -165,6 +166,8 @@ void mmu_cleanup_all(void)
radix__mmu_cleanup_all();
else if (mmu_hash_ops.hpte_clear_all)
mmu_hash_ops.hpte_clear_all();
reset_sprs();
}
#ifdef CONFIG_MEMORY_HOTPLUG