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b4a839009a
Testing with KSM active in the host showed occasional corruption of guest memory. Typically a page that should have contained zeroes would contain values that look like the contents of a user process stack (values such as 0x0000_3fff_xxxx_xxx). Code inspection in kvmppc_h_protect revealed that there was a race condition with the possibility of granting write access to a page which is read-only in the host page tables. The code attempts to keep the host mapping read-only if the host userspace PTE is read-only, but if that PTE had been temporarily made invalid for any reason, the read-only check would not trigger and the host HPTE could end up read-write. Examination of the guest HPT in the failure situation revealed that there were indeed shared pages which should have been read-only that were mapped read-write. To close this race, we don't let a page go from being read-only to being read-write, as far as the real HPTE mapping the page is concerned (the guest view can go to read-write, but the actual mapping stays read-only). When the guest tries to write to the page, we take an HDSI and let kvmppc_book3s_hv_page_fault take care of providing a writable HPTE for the page. This eliminates the occasional corruption of shared pages that was previously seen with KSM active. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de> |
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| .. | ||
| book3s.c | ||
| book3s.h | ||
| book3s_32_mmu.c | ||
| book3s_32_mmu_host.c | ||
| book3s_32_sr.S | ||
| book3s_64_mmu.c | ||
| book3s_64_mmu_host.c | ||
| book3s_64_mmu_hv.c | ||
| book3s_64_slb.S | ||
| book3s_64_vio.c | ||
| book3s_64_vio_hv.c | ||
| book3s_emulate.c | ||
| book3s_exports.c | ||
| book3s_hv.c | ||
| book3s_hv_builtin.c | ||
| book3s_hv_interrupts.S | ||
| book3s_hv_ras.c | ||
| book3s_hv_rm_mmu.c | ||
| book3s_hv_rm_xics.c | ||
| book3s_hv_rmhandlers.S | ||
| book3s_interrupts.S | ||
| book3s_mmu_hpte.c | ||
| book3s_paired_singles.c | ||
| book3s_pr.c | ||
| book3s_pr_papr.c | ||
| book3s_rmhandlers.S | ||
| book3s_rtas.c | ||
| book3s_segment.S | ||
| book3s_xics.c | ||
| book3s_xics.h | ||
| booke.c | ||
| booke.h | ||
| booke_emulate.c | ||
| booke_interrupts.S | ||
| bookehv_interrupts.S | ||
| e500.c | ||
| e500.h | ||
| e500_emulate.c | ||
| e500_mmu.c | ||
| e500_mmu_host.c | ||
| e500_mmu_host.h | ||
| e500mc.c | ||
| emulate.c | ||
| emulate_loadstore.c | ||
| fpu.S | ||
| irq.h | ||
| Kconfig | ||
| Makefile | ||
| mpic.c | ||
| powerpc.c | ||
| timing.c | ||
| timing.h | ||
| trace.h | ||
| trace_booke.h | ||
| trace_pr.h | ||