Am 14.01.2011 02:51, Huang Ying wrote: > On Thu, 2011-01-13 at 17:01 +0800, Jan Kiszka wrote: >> Am 13.01.2011 09:34, Huang Ying wrote: >>> In Linux kernel HWPoison processing implementation, the virtual >>> address in processes mapping the error physical memory page is marked >>> as HWPoison. So that, the further accessing to the virtual >>> address will kill corresponding processes with SIGBUS. >>> >>> If the error physical memory page is used by a KVM guest, the SIGBUS >>> will be sent to QEMU, and QEMU will simulate a MCE to report that >>> memory error to the guest OS. If the guest OS can not recover from >>> the error (for example, the page is accessed by kernel code), guest OS >>> will reboot the system. But because the underlying host virtual >>> address backing the guest physical memory is still poisoned, if the >>> guest system accesses the corresponding guest physical memory even >>> after rebooting, the SIGBUS will still be sent to QEMU and MCE will be >>> simulated. That is, guest system can not recover via rebooting. >>> >>> In fact, across rebooting, the contents of guest physical memory page >>> need not to be kept. We can allocate a new host physical page to >>> back the corresponding guest physical address. >>> >>> This patch fixes this issue in QEMU via calling qemu_ram_remap() to >>> clear the corresponding page table entry, so that make it possible to >>> allocate a new page to recover the issue. >>> >>> Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx> >>> --- >>> kvm.h | 2 ++ >>> target-i386/kvm.c | 39 +++++++++++++++++++++++++++++++++++++++ >>> 2 files changed, 41 insertions(+) >>> >>> --- a/target-i386/kvm.c >>> +++ b/target-i386/kvm.c >>> @@ -580,6 +580,42 @@ static int kvm_get_supported_msrs(void) >>> return ret; >>> } >>> >>> +struct HWPoisonPage; >>> +typedef struct HWPoisonPage HWPoisonPage; >>> +struct HWPoisonPage >>> +{ >>> + ram_addr_t ram_addr; >>> + QLIST_ENTRY(HWPoisonPage) list; >>> +}; >>> + >>> +static QLIST_HEAD(hwpoison_page_list, HWPoisonPage) hwpoison_page_list = >>> + QLIST_HEAD_INITIALIZER(hwpoison_page_list); >>> + >>> +void kvm_unpoison_all(void *param) >> >> Minor nit: This can be static now. > > In uq/master, it can be make static. But in kvm/master, kvm_arch_init > is not compiled because of conditional compiling, so we will get warning > and error for unused symbol. Should we consider kvm/master in this > patch? qemu-kvm is very close to switching to upstream kvm_*init. As long as it requires this service in its own modules, it will have to patch this detail. It does this for other functions already. > >>> +{ >>> + HWPoisonPage *page, *next_page; >>> + >>> + QLIST_FOREACH_SAFE(page, &hwpoison_page_list, list, next_page) { >>> + QLIST_REMOVE(page, list); >>> + qemu_ram_remap(page->ram_addr, TARGET_PAGE_SIZE); >>> + qemu_free(page); >>> + } >>> +} >>> + >>> +static void kvm_hwpoison_page_add(ram_addr_t ram_addr) >>> +{ >>> + HWPoisonPage *page; >>> + >>> + QLIST_FOREACH(page, &hwpoison_page_list, list) { >>> + if (page->ram_addr == ram_addr) >>> + return; >>> + } >>> + >>> + page = qemu_malloc(sizeof(HWPoisonPage)); >>> + page->ram_addr = ram_addr; >>> + QLIST_INSERT_HEAD(&hwpoison_page_list, page, list); >>> +} >>> + >>> int kvm_arch_init(void) >>> { >>> uint64_t identity_base = 0xfffbc000; >>> @@ -632,6 +668,7 @@ int kvm_arch_init(void) >>> fprintf(stderr, "e820_add_entry() table is full\n"); >>> return ret; >>> } >>> + qemu_register_reset(kvm_unpoison_all, NULL); >>> >>> return 0; >>> } >>> @@ -1940,6 +1977,7 @@ int kvm_on_sigbus_vcpu(CPUState *env, in >>> hardware_memory_error(); >>> } >>> } >>> + kvm_hwpoison_page_add(ram_addr); >>> >>> if (code == BUS_MCEERR_AR) { >>> /* Fake an Intel architectural Data Load SRAR UCR */ >>> @@ -1984,6 +2022,7 @@ int kvm_on_sigbus(int code, void *addr) >>> "QEMU itself instead of guest system!: %p\n", addr); >>> return 0; >>> } >>> + kvm_hwpoison_page_add(ram_addr); >>> kvm_mce_inj_srao_memscrub2(first_cpu, paddr); >>> } else >>> #endif >>> --- a/kvm.h >>> +++ b/kvm.h >>> @@ -188,6 +188,8 @@ int kvm_physical_memory_addr_from_ram(ra >>> target_phys_addr_t *phys_addr); >>> #endif >>> >>> +void kvm_unpoison_all(void *param); >>> + >> >> To be removed if kvm_unpoison_all is static. >> >>> #endif >>> int kvm_set_ioeventfd_mmio_long(int fd, uint32_t adr, uint32_t val, bool assign); >>> >>> >> >> As indicated, I'm sitting on lots of fixes and refactorings of the MCE >> user space code. How do you test your patches? Any suggestions how to do >> this efficiently would be warmly welcome. > > We use a self-made test script to test. Repository is at: > > git://git.kernel.org/pub/scm/utils/cpu/mce/mce-test.git > > The kvm test script is in kvm sub-directory. > > The qemu patch attached is need by the test script. > Yeah, I already found this yesterday and started reading. I was just searching for p2v in qemu, but now it's clear where it comes from. Will have a look (if you want to preview my changes: git://git.kiszka.org/qemu-kvm.git queues/kvm-upstream). I was almost about to use MADV_HWPOISON instead of the injection module. Is there a way to recover the fake corruption afterward? I think that would allow to move some of the test logic into qemu and avoid p2v which - IIRC - was disliked upstream. Also, is there a way to simulate corrected errors (BUS_MCEERR_AO)? Thanks, Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html