kernel/arch/powerpc/kvm, branch linux-4.1.y

KVM: PPC: Book3S PR: Check copy_to/from_user return values

2018-05-23T01:36:23Z

[ Upstream commit 67325e988faea735d663799b6d152b5f4254093c ] The PR KVM implementation of the PAPR HPT hypercalls (H_ENTER etc.) access an image of the HPT in userspace memory using copy_from_user and copy_to_user. Recently, the declarations of those functions were annotated to indicate that the return value must be checked. Since this code doesn't currently check the return value, this causes compile warnings like the ones shown below, and since on PPC the default is to compile arch/powerpc with -Werror, this causes the build to fail. To fix this, we check the return values, and if non-zero, fail the hypercall being processed with a H_FUNCTION error return value. There is really no good error return value to use since PAPR didn't envisage the possibility that the hypervisor may not be able to access the guest's HPT, and H_FUNCTION (function not supported) seems as good as any. The typical compile warnings look like this: CC arch/powerpc/kvm/book3s_pr_papr.o /home/paulus/kernel/kvm/arch/powerpc/kvm/book3s_pr_papr.c: In function ‘kvmppc_h_pr_enter’: /home/paulus/kernel/kvm/arch/powerpc/kvm/book3s_pr_papr.c:53:2: error: ignoring return value of ‘copy_from_user’, declared with attribute warn_unused_result [-Werror=unused-result] copy_from_user(pteg, (void __user *)pteg_addr, sizeof(pteg)); ^ /home/paulus/kernel/kvm/arch/powerpc/kvm/book3s_pr_papr.c:74:2: error: ignoring return value of ‘copy_to_user’, declared with attribute warn_unused_result [-Werror=unused-result] copy_to_user((void __user *)pteg_addr, hpte, HPTE_SIZE); ^ ... etc. Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin

KVM: PPC: Book3S PR: Exit KVM on failed mapping

2018-05-23T01:33:49Z

[ Upstream commit bd9166ffe624000140fc6b606b256df01fc0d060 ] At the moment kvmppc_mmu_map_page() returns -1 if mmu_hash_ops.hpte_insert() fails for any reason so the page fault handler resumes the guest and it faults on the same address again. This adds distinction to kvmppc_mmu_map_page() to return -EIO if mmu_hash_ops.hpte_insert() failed for a reason other than full pteg. At the moment only pSeries_lpar_hpte_insert() returns -2 if plpar_pte_enter() failed with a code other than H_PTEG_FULL. Other mmu_hash_ops.hpte_insert() instances can only fail with -1 "full pteg". With this change, if PR KVM fails to update HPT, it can signal the userspace about this instead of returning to guest and having the very same page fault over and over again. Signed-off-by: Alexey Kardashevskiy Reviewed-by: David Gibson Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin

powerpc/64s: Simple RFI macro conversions

2018-03-04T15:28:35Z

commit 222f20f140623ef6033491d0103ee0875fe87d35 upstream. This commit does simple conversions of rfi/rfid to the new macros that include the expected destination context. By simple we mean cases where there is a single well known destination context, and it's simply a matter of substituting the instruction for the appropriate macro. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman [Balbir fixed issues with backporting to stable] Signed-off-by: Balbir Singh Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

KVM: PPC: Book3S PR: Fix illegal opcode emulation

2018-01-17T17:29:25Z

[ Upstream commit 708e75a3ee750dce1072134e630d66c4e6eaf63c ] If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() returned EMULATE_FAIL, so the guest gets an program interrupt for the illegal opcode. However, the kvmppc_emulate_instruction() also tried to inject a program exception for this already, so the program interrupt gets injected twice and the return address in srr0 gets destroyed. All other callers of kvmppc_emulate_instruction() are also injecting a program interrupt, and since the callers have the right knowledge about the srr1 flags that should be used, it is the function kvmppc_emulate_instruction() that should _not_ inject program interrupts, so remove the kvmppc_core_queue_program() here. This fixes the issue discovered by Laurent Vivier with kvm-unit-tests where the logs are filled with these messages when the test tries to execute an illegal instruction: Couldn't emulate instruction 0x00000000 (op 0 xop 0) kvmppc_handle_exit_pr: emulation at 700 failed (00000000) Signed-off-by: Thomas Huth Reviewed-by: Alexander Graf Tested-by: Laurent Vivier Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin

KVM: PPC: Book 3S: XICS: correct the real mode ICP rejecting counter

2017-12-07T02:19:57Z

[ Upstream commit 37451bc95dee0e666927d6ffdda302dbbaaae6fa ] Some counters are added in Commit 6e0365b78273 ("KVM: PPC: Book3S HV: Add ICP real mode counters"), to provide some performance statistics to determine whether further optimizing is needed for real mode functions. The n_reject counter counts how many times ICP rejects an irq because of priority in real mode. The redelivery of an lsi that is still asserted after eoi doesn't fall into this category, so the increasement there is removed. Also, it needs to be increased in icp_rm_deliver_irq() if it rejects another one. Signed-off-by: Li Zhong Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin

KVM: PPC: Book3S: Fix race and leak in kvm_vm_ioctl_create_spapr_tce()

2017-11-05T00:17:50Z

[ Upstream commit 47c5310a8dbe7c2cb9f0083daa43ceed76c257fa ] Nixiaoming pointed out that there is a memory leak in kvm_vm_ioctl_create_spapr_tce() if the call to anon_inode_getfd() fails; the memory allocated for the kvmppc_spapr_tce_table struct is not freed, and nor are the pages allocated for the iommu tables. In addition, we have already incremented the process's count of locked memory pages, and this doesn't get restored on error. David Hildenbrand pointed out that there is a race in that the function checks early on that there is not already an entry in the stt->iommu_tables list with the same LIOBN, but an entry with the same LIOBN could get added between then and when the new entry is added to the list. This fixes all three problems. To simplify things, we now call anon_inode_getfd() before placing the new entry in the list. The check for an existing entry is done while holding the kvm->lock mutex, immediately before adding the new entry to the list. Finally, on failure we now call kvmppc_account_memlimit to decrement the process's count of locked memory pages. Reported-by: Nixiaoming Reported-by: David Hildenbrand Signed-off-by: Paul Mackerras Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin

KVM: PPC: Book3S HV: Save/restore host values of debug registers

2017-09-10T20:35:47Z

[ Upstream commit 7ceaa6dcd8c6f59588428cec37f3c8093dd1011f ] At present, HV KVM on POWER8 and POWER9 machines loses any instruction or data breakpoint set in the host whenever a guest is run. Instruction breakpoints are currently only used by xmon, but ptrace and the perf_event subsystem can set data breakpoints as well as xmon. To fix this, we save the host values of the debug registers (CIABR, DAWR and DAWRX) before entering the guest and restore them on exit. To provide space to save them in the stack frame, we expand the stack frame allocated by kvmppc_hv_entry() from 112 to 144 bytes. Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08) Cc: stable@vger.kernel.org # v3.14+ Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin

KVM: PPC: Book3S HV: Restore critical SPRs to host values on guest exit

2017-09-10T20:35:46Z

[ Upstream commit 4c3bb4ccd074e1a0552078c0bf94c662367a1658 ] This restores several special-purpose registers (SPRs) to sane values on guest exit that were missed before. TAR and VRSAVE are readable and writable by userspace, and we need to save and restore them to prevent the guest from potentially affecting userspace execution (not that TAR or VRSAVE are used by any known program that run uses the KVM_RUN ioctl). We save/restore these in kvmppc_vcpu_run_hv() rather than on every guest entry/exit. FSCR affects userspace execution in that it can prohibit access to certain facilities by userspace. We restore it to the normal value for the task on exit from the KVM_RUN ioctl. IAMR is normally 0, and is restored to 0 on guest exit. However, with a radix host on POWER9, it is set to a value that prevents the kernel from executing user-accessible memory. On POWER9, we save IAMR on guest entry and restore it on guest exit to the saved value rather than 0. On POWER8 we continue to set it to 0 on guest exit. PSPB is normally 0. We restore it to 0 on guest exit to prevent userspace taking advantage of the guest having set it non-zero (which would allow userspace to set its SMT priority to high). UAMOR is normally 0. We restore it to 0 on guest exit to prevent the AMR from being used as a covert channel between userspace processes, since the AMR is not context-switched at present. Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08) Cc: stable@vger.kernel.org # v3.14+ Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin

KVM: PPC: Book3S HV: Context-switch EBB registers properly

2017-09-10T20:35:46Z

[ Upstream commit ca8efa1df1d15a1795a2da57f9f6aada6ed6b946 ] This adds code to save the values of three SPRs (special-purpose registers) used by userspace to control event-based branches (EBBs), which are essentially interrupts that get delivered directly to userspace. These registers are loaded up with guest values when entering the guest, and their values are saved when exiting the guest, but we were not saving the host values and restoring them before going back to userspace. On POWER8 this would only affect userspace programs which explicitly request the use of EBBs and also use the KVM_RUN ioctl, since the only source of EBBs on POWER8 is the PMU, and there is an explicit enable bit in the PMU registers (and those PMU registers do get properly context-switched between host and guest). On POWER9 there is provision for externally-generated EBBs, and these are not subject to the control in the PMU registers. Since these registers only affect userspace, we can save them when we first come in from userspace and restore them before returning to userspace, rather than saving/restoring the host values on every guest entry/exit. Similarly, we don't need to worry about their values on offline secondary threads since they execute in the context of the idle task, which never executes in userspace. Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08) Cc: stable@vger.kernel.org # v3.14+ Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin

KVM: PPC: Book3S HV: Preserve userspace HTM state properly

2017-07-31T17:37:47Z

[ Upstream commit 46a704f8409f79fd66567ad3f8a7304830a84293 ] If userspace attempts to call the KVM_RUN ioctl when it has hardware transactional memory (HTM) enabled, the values that it has put in the HTM-related SPRs TFHAR, TFIAR and TEXASR will get overwritten by guest values. To fix this, we detect this condition and save those SPR values in the thread struct, and disable HTM for the task. If userspace goes to access those SPRs or the HTM facility in future, a TM-unavailable interrupt will occur and the handler will reload those SPRs and re-enable HTM. If userspace has started a transaction and suspended it, we would currently lose the transactional state in the guest entry path and would almost certainly get a "TM Bad Thing" interrupt, which would cause the host to crash. To avoid this, we detect this case and return from the KVM_RUN ioctl with an EINVAL error, with the KVM exit reason set to KVM_EXIT_FAIL_ENTRY. Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08) Cc: stable@vger.kernel.org # v3.14+ Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin