On Tue, Apr 05, 2022 at 01:47:44PM -0600, Jane Chu wrote: > The set_memory_uc() approach doesn't work well in all cases. > For example, when "The VMM unmapped the bad page from guest > physical space and passed the machine check to the guest." > "The guest gets virtual #MC on an access to that page. > When the guest tries to do set_memory_uc() and instructs > cpa_flush() to do clean caches that results in taking another > fault / exception perhaps because the VMM unmapped the page > from the guest." I presume this is quoting someone... > Since the driver has special knowledge to handle NP or UC, > let's mark the poisoned page with NP and let driver handle it s/let's mark/mark/ > when it comes down to repair. > > Please refer to discussions here for more details. > https://lore.kernel.org/all/CAPcyv4hrXPb1tASBZUg-GgdVs0OOFKXMXLiHmktg_kFi7YBMyQ@xxxxxxxxxxxxxx/ > > Now since poisoned page is marked as not-present, in order to > avoid writing to a 'np' page and trigger kernel Oops, also fix You can write it out: "non-present page..." > pmem_do_write(). > > Fixes: 284ce4011ba6 ("x86/memory_failure: Introduce {set, clear}_mce_nospec()") > Signed-off-by: Jane Chu <jane.chu@xxxxxxxxxx> > --- > arch/x86/kernel/cpu/mce/core.c | 6 +++--- > arch/x86/mm/pat/set_memory.c | 18 ++++++------------ > drivers/nvdimm/pmem.c | 31 +++++++------------------------ > include/linux/set_memory.h | 4 ++-- > 4 files changed, 18 insertions(+), 41 deletions(-) For such mixed subsystem patches we probably should talk about who picks them up, eventually... > diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c > index 981496e6bc0e..fa67bb9d1afe 100644 > --- a/arch/x86/kernel/cpu/mce/core.c > +++ b/arch/x86/kernel/cpu/mce/core.c > @@ -579,7 +579,7 @@ static int uc_decode_notifier(struct notifier_block *nb, unsigned long val, > > pfn = mce->addr >> PAGE_SHIFT; > if (!memory_failure(pfn, 0)) { > - set_mce_nospec(pfn, whole_page(mce)); > + set_mce_nospec(pfn); > mce->kflags |= MCE_HANDLED_UC; > } > > @@ -1316,7 +1316,7 @@ static void kill_me_maybe(struct callback_head *cb) > > ret = memory_failure(p->mce_addr >> PAGE_SHIFT, flags); > if (!ret) { > - set_mce_nospec(p->mce_addr >> PAGE_SHIFT, p->mce_whole_page); > + set_mce_nospec(p->mce_addr >> PAGE_SHIFT); > sync_core(); > return; > } > @@ -1342,7 +1342,7 @@ static void kill_me_never(struct callback_head *cb) > p->mce_count = 0; > pr_err("Kernel accessed poison in user space at %llx\n", p->mce_addr); > if (!memory_failure(p->mce_addr >> PAGE_SHIFT, 0)) > - set_mce_nospec(p->mce_addr >> PAGE_SHIFT, p->mce_whole_page); > + set_mce_nospec(p->mce_addr >> PAGE_SHIFT); > } Both that ->mce_whole_page and whole_page() look unused after this. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
