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s390/nmi: disable interrupts on extended save area update

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Updating of the pointer to machine check extended save area
on the IPL CPU needs the lowcore protection to be disabled.
Disable interrupts while the protection is off to avoid
unnoticed writes to the lowcore.

Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Alexander Gordeev
2021-12-10 16:32:11 +01:00
committed by Heiko Carstens
parent cff2d3abc8
commit c7ed509b21
4 changed files with 29 additions and 33 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
arch/s390/kernel/smp.c
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@@ -212,7 +212,7 @@ static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu)
lc->return_lpswe = gen_lpswe(__LC_RETURN_PSW);
lc->return_mcck_lpswe = gen_lpswe(__LC_RETURN_MCCK_PSW);
lc->preempt_count = PREEMPT_DISABLED;
if (nmi_alloc_per_cpu(lc))
if (nmi_alloc_mcesa(&lc->mcesad))
goto out;
lowcore_ptr[cpu] = lc;
pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, (u32)(unsigned long) lc);
@@ -239,7 +239,7 @@ static void pcpu_free_lowcore(struct pcpu *pcpu)
mcck_stack = lc->mcck_stack - STACK_INIT_OFFSET;
pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, 0);
lowcore_ptr[cpu] = NULL;
nmi_free_per_cpu(lc);
nmi_free_mcesa(&lc->mcesad);
stack_free(async_stack);
stack_free(mcck_stack);
free_pages(nodat_stack, THREAD_SIZE_ORDER);
@@ -1271,14 +1271,15 @@ static int __init smp_reinit_ipl_cpu(void)
{
unsigned long async_stack, nodat_stack, mcck_stack;
struct lowcore *lc, *lc_ipl;
unsigned long flags;
unsigned long flags, cr0;
u64 mcesad;
lc_ipl = lowcore_ptr[0];
lc = (struct lowcore *) __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);
nodat_stack = __get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER);
async_stack = stack_alloc();
mcck_stack = stack_alloc();
if (!lc || !nodat_stack || !async_stack || !mcck_stack)
if (!lc || !nodat_stack || !async_stack || !mcck_stack || nmi_alloc_mcesa(&mcesad))
panic("Couldn't allocate memory");
local_irq_save(flags);
@@ -1287,6 +1288,10 @@ static int __init smp_reinit_ipl_cpu(void)
S390_lowcore.nodat_stack = nodat_stack + STACK_INIT_OFFSET;
S390_lowcore.async_stack = async_stack + STACK_INIT_OFFSET;
S390_lowcore.mcck_stack = mcck_stack + STACK_INIT_OFFSET;
__ctl_store(cr0, 0, 0);
__ctl_clear_bit(0, 28); /* disable lowcore protection */
S390_lowcore.mcesad = mcesad;
__ctl_load(cr0, 0, 0);
lowcore_ptr[0] = lc;
local_mcck_enable();
local_irq_restore(flags);