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authorTony Luck <tony.luck@intel.com>2020-05-20 09:35:46 -0700
committerThomas Gleixner <tglx@linutronix.de>2020-06-11 15:19:17 +0200
commit17fae1294ad9d711b2c3dd0edef479d40c76a5e8 (patch)
tree13d6d176ac7bf835ab28f7b5bfe7e08996c9decb /include/linux
parentf77d26a9fc525286bcef3d4f98b52e17482cf49c (diff)
x86/{mce,mm}: Unmap the entire page if the whole page is affected and poisoned
An interesting thing happened when a guest Linux instance took a machine check. The VMM unmapped the bad page from guest physical space and passed the machine check to the guest. Linux took all the normal actions to offline the page from the process that was using it. But then guest Linux crashed because it said there was a second machine check inside the kernel with this stack trace: do_memory_failure set_mce_nospec set_memory_uc _set_memory_uc change_page_attr_set_clr cpa_flush clflush_cache_range_opt This was odd, because a CLFLUSH instruction shouldn't raise a machine check (it isn't consuming the data). Further investigation showed that the VMM had passed in another machine check because is appeared that the guest was accessing the bad page. Fix is to check the scope of the poison by checking the MCi_MISC register. If the entire page is affected, then unmap the page. If only part of the page is affected, then mark the page as uncacheable. This assumes that VMMs will do the logical thing and pass in the "whole page scope" via the MCi_MISC register (since they unmapped the entire page). [ bp: Adjust to x86/entry changes. ] Fixes: 284ce4011ba6 ("x86/memory_failure: Introduce {set, clear}_mce_nospec()") Reported-by: Jue Wang <juew@google.com> Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Jue Wang <juew@google.com> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20200520163546.GA7977@agluck-desk2.amr.corp.intel.com
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/sched.h4
-rw-r--r--include/linux/set_memory.h2
2 files changed, 4 insertions, 2 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c5d96e3e7fff..62c1de522fc5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1304,7 +1304,9 @@ struct task_struct {
#ifdef CONFIG_X86_MCE
u64 mce_addr;
- u64 mce_status;
+ __u64 mce_ripv : 1,
+ mce_whole_page : 1,
+ __mce_reserved : 62;
struct callback_head mce_kill_me;
#endif
diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h
index 86281ac7c305..860e0f843c12 100644
--- a/include/linux/set_memory.h
+++ b/include/linux/set_memory.h
@@ -26,7 +26,7 @@ static inline int set_direct_map_default_noflush(struct page *page)
#endif
#ifndef set_mce_nospec
-static inline int set_mce_nospec(unsigned long pfn)
+static inline int set_mce_nospec(unsigned long pfn, bool unmap)
{
return 0;
}