From 196f878a7ac2e727a1ded5197e552e6e2d3dfe2c Mon Sep 17 00:00:00 2001 From: James Morse Date: Tue, 20 Jun 2017 17:11:48 +0100 Subject: KVM: arm/arm64: Signal SIGBUS when stage2 discovers hwpoison memory Once we enable ARCH_SUPPORTS_MEMORY_FAILURE on arm64, notifications for broken memory can call memory_failure() in mm/memory-failure.c to offline pages of memory, possibly signalling user space processes and notifying all the in-kernel users. memory_failure() has two modes, early and late. Early is used by machine-managers like Qemu to receive a notification when a memory error is notified to the host. These can then be relayed to the guest before the affected page is accessed. To enable this, the process must set PR_MCE_KILL_EARLY in PR_MCE_KILL_SET using the prctl() syscall. Once the early notification has been handled, nothing stops the machine-manager or guest from accessing the affected page. If the machine-manager does this the page will fail to be mapped and SIGBUS will be sent. This patch adds the equivalent path for when the guest accesses the page, sending SIGBUS to the machine-manager. These two signals can be distinguished by the machine-manager using their si_code: BUS_MCEERR_AO for 'action optional' early notifications, and BUS_MCEERR_AR for 'action required' synchronous/late notifications. Do as x86 does, and deliver the SIGBUS when we discover pfn == KVM_PFN_ERR_HWPOISON. Use the hugepage size as si_addr_lsb if this vma was allocated as a hugepage. Transparent hugepages will be split by memory_failure() before we see them here. Cc: Punit Agrawal Signed-off-by: James Morse Signed-off-by: Marc Zyngier --- virt/kvm/arm/mmu.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c index e2e5effba2a9..f2d5b6cf06ae 100644 --- a/virt/kvm/arm/mmu.c +++ b/virt/kvm/arm/mmu.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -1261,6 +1262,24 @@ static void coherent_cache_guest_page(struct kvm_vcpu *vcpu, kvm_pfn_t pfn, __coherent_cache_guest_page(vcpu, pfn, size); } +static void kvm_send_hwpoison_signal(unsigned long address, + struct vm_area_struct *vma) +{ + siginfo_t info; + + info.si_signo = SIGBUS; + info.si_errno = 0; + info.si_code = BUS_MCEERR_AR; + info.si_addr = (void __user *)address; + + if (is_vm_hugetlb_page(vma)) + info.si_addr_lsb = huge_page_shift(hstate_vma(vma)); + else + info.si_addr_lsb = PAGE_SHIFT; + + send_sig_info(SIGBUS, &info, current); +} + static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, struct kvm_memory_slot *memslot, unsigned long hva, unsigned long fault_status) @@ -1330,6 +1349,10 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, smp_rmb(); pfn = gfn_to_pfn_prot(kvm, gfn, write_fault, &writable); + if (pfn == KVM_PFN_ERR_HWPOISON) { + kvm_send_hwpoison_signal(hva, vma); + return 0; + } if (is_error_noslot_pfn(pfn)) return -EFAULT; -- cgit v1.2.1