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2022-04-20KVM: x86/emulator: Defer not-present segment check in ↵Hou Wenlong1-5/+9
__load_segment_descriptor() [ Upstream commit ca85f002258fdac3762c57d12d5e6e401b6a41af ] Per Intel's SDM on the "Instruction Set Reference", when loading segment descriptor, not-present segment check should be after all type and privilege checks. But the emulator checks it first, then #NP is triggered instead of #GP if privilege fails and segment is not present. Put not-present segment check after type and privilege checks in __load_segment_descriptor(). Fixes: 38ba30ba51a00 (KVM: x86 emulator: Emulate task switch in emulator.c) Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com> Message-Id: <52573c01d369f506cadcf7233812427cf7db81a7.1644292363.git.houwenlong.hwl@antgroup.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-11-22KVM: x86: clflushopt should be treated as a no-op by emulationDavid Edmondson1-1/+7
commit 51b958e5aeb1e18c00332e0b37c5d4e95a3eff84 upstream. The instruction emulator ignores clflush instructions, yet fails to support clflushopt. Treat both similarly. Fixes: 13e457e0eebf ("KVM: x86: Emulator does not decode clflush well") Signed-off-by: David Edmondson <david.edmondson@oracle.com> Message-Id: <20201103120400.240882-1-david.edmondson@oracle.com> Reviewed-by: Joao Martins <joao.m.martins@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-29KVM: x86: emulating RDPID failure shall return #UD rather than #GPRobert Hoo1-1/+1
[ Upstream commit a9e2e0ae686094571378c72d8146b5a1a92d0652 ] Per Intel's SDM, RDPID takes a #UD if it is unsupported, which is more or less what KVM is emulating when MSR_TSC_AUX is not available. In fact, there are no scenarios in which RDPID is supposed to #GP. Fixes: fb6d4d340e ("KVM: x86: emulate RDPID") Signed-off-by: Robert Hoo <robert.hu@linux.intel.com> Message-Id: <1598581422-76264-1-git-send-email-robert.hu@linux.intel.com> Reviewed-by: Jim Mattson <jmattson@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-03-20KVM: x86: clear stale x86_emulate_ctxt->intercept valueVitaly Kuznetsov1-0/+1
commit 342993f96ab24d5864ab1216f46c0b199c2baf8e upstream. After commit 07721feee46b ("KVM: nVMX: Don't emulate instructions in guest mode") Hyper-V guests on KVM stopped booting with: kvm_nested_vmexit: rip fffff802987d6169 reason EPT_VIOLATION info1 181 info2 0 int_info 0 int_info_err 0 kvm_page_fault: address febd0000 error_code 181 kvm_emulate_insn: 0:fffff802987d6169: f3 a5 kvm_emulate_insn: 0:fffff802987d6169: f3 a5 FAIL kvm_inj_exception: #UD (0x0) "f3 a5" is a "rep movsw" instruction, which should not be intercepted at all. Commit c44b4c6ab80e ("KVM: emulate: clean up initializations in init_decode_cache") reduced the number of fields cleared by init_decode_cache() claiming that they are being cleared elsewhere, 'intercept', however, is left uncleared if the instruction does not have any of the "slow path" flags (NotImpl, Stack, Op3264, Sse, Mmx, CheckPerm, NearBranch, No16 and of course Intercept itself). Fixes: c44b4c6ab80e ("KVM: emulate: clean up initializations in init_decode_cache") Fixes: 07721feee46b ("KVM: nVMX: Don't emulate instructions in guest mode") Cc: stable@vger.kernel.org Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-28KVM: x86: emulate RDPIDPaolo Bonzini1-1/+21
commit fb6d4d340e0532032c808a9933eaaa7b8de435ab upstream. This is encoded as F3 0F C7 /7 with a register argument. The register argument is the second array in the group9 GroupDual, while F3 is the fourth element of a Prefix. Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-15KVM: x86: Protect x86_decode_insn from Spectre-v1/L1TF attacksMarios Pomonis1-3/+9
commit 3c9053a2cae7ba2ba73766a34cea41baa70f57f7 upstream. This fixes a Spectre-v1/L1TF vulnerability in x86_decode_insn(). kvm_emulate_instruction() (an ancestor of x86_decode_insn()) is an exported symbol, so KVM should treat it conservatively from a security perspective. Fixes: 045a282ca415 ("KVM: emulator: implement fninit, fnstsw, fnstcw") Signed-off-by: Nick Finco <nifi@google.com> Signed-off-by: Marios Pomonis <pomonis@google.com> Reviewed-by: Andrew Honig <ahonig@google.com> Cc: stable@vger.kernel.org Reviewed-by: Jim Mattson <jmattson@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-15KVM: x86: Refactor prefix decoding to prevent Spectre-v1/L1TF attacksMarios Pomonis1-2/+14
commit 125ffc5e0a56a3eded608dc51e09d5ebf72cf652 upstream. This fixes Spectre-v1/L1TF vulnerabilities in vmx_read_guest_seg_selector(), vmx_read_guest_seg_base(), vmx_read_guest_seg_limit() and vmx_read_guest_seg_ar(). When invoked from emulation, these functions contain index computations based on the (attacker-influenced) segment value. Using constants prevents the attack. Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-10-05KVM: x86: set ctxt->have_exception in x86_decode_insn()Jan Dakinevich1-0/+2
commit c8848cee74ff05638e913582a476bde879c968ad upstream. x86_emulate_instruction() takes into account ctxt->have_exception flag during instruction decoding, but in practice this flag is never set in x86_decode_insn(). Fixes: 6ea6e84309ca ("KVM: x86: inject exceptions produced by x86_decode_insn") Cc: stable@vger.kernel.org Cc: Denis Lunev <den@virtuozzo.com> Cc: Roman Kagan <rkagan@virtuozzo.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Signed-off-by: Jan Dakinevich <jan.dakinevich@virtuozzo.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-27KVM: x86: Don't clear EFER during SMM transitions for 32-bit vCPUSean Christopherson1-10/+11
commit 8f4dc2e77cdfaf7e644ef29693fa229db29ee1de upstream. Neither AMD nor Intel CPUs have an EFER field in the legacy SMRAM save state area, i.e. don't save/restore EFER across SMM transitions. KVM somewhat models this, e.g. doesn't clear EFER on entry to SMM if the guest doesn't support long mode. But during RSM, KVM unconditionally clears EFER so that it can get back to pure 32-bit mode in order to start loading CRs with their actual non-SMM values. Clear EFER only when it will be written when loading the non-SMM state so as to preserve bits that can theoretically be set on 32-bit vCPUs, e.g. KVM always emulates EFER_SCE. And because CR4.PAE is cleared only to play nice with EFER, wrap that code in the long mode check as well. Note, this may result in a compiler warning about cr4 being consumed uninitialized. Re-read CR4 even though it's technically unnecessary, as doing so allows for more readable code and RSM emulation is not a performance critical path. Fixes: 660a5d517aaab ("KVM: x86: save/load state on SMM switch") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-06-16kvm: x86: use correct privilege level for sgdt/sidt/fxsave/fxrstor accessPaolo Bonzini1-6/+6
commit 3c9fa24ca7c9c47605672916491f79e8ccacb9e6 upstream. The functions that were used in the emulation of fxrstor, fxsave, sgdt and sidt were originally meant for task switching, and as such they did not check privilege levels. This is very bad when the same functions are used in the emulation of unprivileged instructions. This is CVE-2018-10853. The obvious fix is to add a new argument to ops->read_std and ops->write_std, which decides whether the access is a "system" access or should use the processor's CPL. Fixes: 129a72a0d3c8 ("KVM: x86: Introduce segmented_write_std", 2017-01-12) Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-06-16KVM: x86: introduce linear_{read,write}_systemPaolo Bonzini1-32/+32
commit 79367a65743975e5cac8d24d08eccc7fdae832b0 upstream. Wrap the common invocation of ctxt->ops->read_std and ctxt->ops->write_std, so as to have a smaller patch when the functions grow another argument. Fixes: 129a72a0d3c8 ("KVM: x86: Introduce segmented_write_std", 2017-01-12) Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-02-13KVM: x86: Make indirect calls in emulator speculation safePeter Zijlstra1-5/+5
(cherry picked from commit 1a29b5b7f347a1a9230c1e0af5b37e3e571588ab) Replace the indirect calls with CALL_NOSPEC. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: David Woodhouse <dwmw@amazon.co.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Ashok Raj <ashok.raj@intel.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Jun Nakajima <jun.nakajima@intel.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: rga@amazon.de Cc: Dave Hansen <dave.hansen@intel.com> Cc: Asit Mallick <asit.k.mallick@intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Jason Baron <jbaron@akamai.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Link: https://lkml.kernel.org/r/20180125095843.595615683@infradead.org [dwmw2: Use ASM_CALL_CONSTRAINT like upstream, now we have it] Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-02-03KVM: X86: Fix operand/address-size during instruction decodingWanpeng Li1-0/+7
[ Upstream commit 3853be2603191829b442b64dac6ae8ba0c027bf9 ] Pedro reported: During tests that we conducted on KVM, we noticed that executing a "PUSH %ES" instruction under KVM produces different results on both memory and the SP register depending on whether EPT support is enabled. With EPT the SP is reduced by 4 bytes (and the written value is 0-padded) but without EPT support it is only reduced by 2 bytes. The difference can be observed when the CS.DB field is 1 (32-bit) but not when it's 0 (16-bit). The internal segment descriptor cache exist even in real/vm8096 mode. The CS.D also should be respected instead of just default operand/address-size/66H prefix/67H prefix during instruction decoding. This patch fixes it by also adjusting operand/address-size according to CS.D. Reported-by: Pedro Fonseca <pfonseca@cs.washington.edu> Tested-by: Pedro Fonseca <pfonseca@cs.washington.edu> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Pedro Fonseca <pfonseca@cs.washington.edu> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-12-29kvm: x86: fix RSM when PCID is non-zeroPaolo Bonzini1-7/+25
commit fae1a3e775cca8c3a9e0eb34443b310871a15a92 upstream. rsm_load_state_64() and rsm_enter_protected_mode() load CR3, then CR4 & ~PCIDE, then CR0, then CR4. However, setting CR4.PCIDE fails if CR3[11:0] != 0. It's probably easier in the long run to replace rsm_enter_protected_mode() with an emulator callback that sets all the special registers (like KVM_SET_SREGS would do). For now, set the PCID field of CR3 only after CR4.PCIDE is 1. Reported-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Laszlo Ersek <lersek@redhat.com> Fixes: 660a5d517aaab9187f93854425c4c63f4a09195c Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-12KVM: x86: fix singlestepping over syscallPaolo Bonzini1-0/+1
commit c8401dda2f0a00cd25c0af6a95ed50e478d25de4 upstream. TF is handled a bit differently for syscall and sysret, compared to the other instructions: TF is checked after the instruction completes, so that the OS can disable #DB at a syscall by adding TF to FMASK. When the sysret is executed the #DB is taken "as if" the syscall insn just completed. KVM emulates syscall so that it can trap 32-bit syscall on Intel processors. Fix the behavior, otherwise you could get #DB on a user stack which is not nice. This does not affect Linux guests, as they use an IST or task gate for #DB. This fixes CVE-2017-7518. Cc: stable@vger.kernel.org Reported-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> [bwh: Backported to 4.9: - kvm_vcpu_check_singlestep() sets some flags differently - Drop changes to kvm_skip_emulated_instruction()] Cc: Ben Hutchings <benh@debian.org> Cc: Salvatore Bonaccorso <carnil@debian.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-07-05KVM: x86: fix emulation of RSM and IRET instructionsLadi Prosek1-7/+9
commit 6ed071f051e12cf7baa1b69d3becb8f232fdfb7b upstream. On AMD, the effect of set_nmi_mask called by emulate_iret_real and em_rsm on hflags is reverted later on in x86_emulate_instruction where hflags are overwritten with ctxt->emul_flags (the kvm_set_hflags call). This manifests as a hang when rebooting Windows VMs with QEMU, OVMF, and >1 vcpu. Instead of trying to merge ctxt->emul_flags into vcpu->arch.hflags after an instruction is emulated, this commit deletes emul_flags altogether and makes the emulator access vcpu->arch.hflags using two new accessors. This way all changes, on the emulator side as well as in functions called from the emulator and accessing vcpu state with emul_to_vcpu, are preserved. More details on the bug and its manifestation with Windows and OVMF: It's a KVM bug in the interaction between SMI/SMM and NMI, specific to AMD. I believe that the SMM part explains why we started seeing this only with OVMF. KVM masks and unmasks NMI when entering and leaving SMM. When KVM emulates the RSM instruction in em_rsm, the set_nmi_mask call doesn't stick because later on in x86_emulate_instruction we overwrite arch.hflags with ctxt->emul_flags, effectively reverting the effect of the set_nmi_mask call. The AMD-specific hflag of interest here is HF_NMI_MASK. When rebooting the system, Windows sends an NMI IPI to all but the current cpu to shut them down. Only after all of them are parked in HLT will the initiating cpu finish the restart. If NMI is masked, other cpus never get the memo and the initiating cpu spins forever, waiting for hal!HalpInterruptProcessorsStarted to drop. That's the symptom we observe. Fixes: a584539b24b8 ("KVM: x86: pass the whole hflags field to emulator and back") Signed-off-by: Ladi Prosek <lprosek@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-01-19KVM: x86: Introduce segmented_write_stdSteve Rutherford1-4/+18
commit 129a72a0d3c8e139a04512325384fe5ac119e74d upstream. Introduces segemented_write_std. Switches from emulated reads/writes to standard read/writes in fxsave, fxrstor, sgdt, and sidt. This fixes CVE-2017-2584, a longstanding kernel memory leak. Since commit 283c95d0e389 ("KVM: x86: emulate FXSAVE and FXRSTOR", 2016-11-09), which is luckily not yet in any final release, this would also be an exploitable kernel memory *write*! Reported-by: Dmitry Vyukov <dvyukov@google.com> Fixes: 96051572c819194c37a8367624b285be10297eca Fixes: 283c95d0e3891b64087706b344a4b545d04a6e62 Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Steve Rutherford <srutherford@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-01-19KVM: x86: emulate FXSAVE and FXRSTORRadim Krčmář1-1/+128
commit 283c95d0e3891b64087706b344a4b545d04a6e62 upstream. Internal errors were reported on 16 bit fxsave and fxrstor with ipxe. Old Intels don't have unrestricted_guest, so we have to emulate them. The patch takes advantage of the hardware implementation. AMD and Intel differ in saving and restoring other fields in first 32 bytes. A test wrote 0xff to the fxsave area, 0 to upper bits of MCSXR in the fxsave area, executed fxrstor, rewrote the fxsave area to 0xee, and executed fxsave: Intel (Nehalem): 7f 1f 7f 7f ff 00 ff 07 ff ff ff ff ff ff 00 00 ff ff ff ff ff ff 00 00 ff ff 00 00 ff ff 00 00 Intel (Haswell -- deprecated FPU CS and FPU DS): 7f 1f 7f 7f ff 00 ff 07 ff ff ff ff 00 00 00 00 ff ff ff ff 00 00 00 00 ff ff 00 00 ff ff 00 00 AMD (Opteron 2300-series): 7f 1f 7f 7f ff 00 ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ff ff 00 00 ff ff 02 00 fxsave/fxrstor will only be emulated on early Intels, so KVM can't do much to improve the situation. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-01-19KVM: x86: add asm_safe wrapperRadim Krčmář1-11/+23
commit aabba3c6abd50b05b1fc2c6ec44244aa6bcda576 upstream. Move the existing exception handling for inline assembly into a macro and switch its return values to X86EMUL type. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-01-19KVM: x86: add Align16 instruction flagRadim Krčmář1-8/+12
commit d3fe959f81024072068e9ed86b39c2acfd7462a9 upstream. Needed for FXSAVE and FXRSTOR. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-01-19KVM: x86: fix emulation of "MOV SS, null selector"Paolo Bonzini1-10/+38
commit 33ab91103b3415e12457e3104f0e4517ce12d0f3 upstream. This is CVE-2017-2583. On Intel this causes a failed vmentry because SS's type is neither 3 nor 7 (even though the manual says this check is only done for usable SS, and the dmesg splat says that SS is unusable!). On AMD it's worse: svm.c is confused and sets CPL to 0 in the vmcb. The fix fabricates a data segment descriptor when SS is set to a null selector, so that CPL and SS.DPL are set correctly in the VMCS/vmcb. Furthermore, only allow setting SS to a NULL selector if SS.RPL < 3; this in turn ensures CPL < 3 because RPL must be equal to CPL. Thanks to Andy Lutomirski and Willy Tarreau for help in analyzing the bug and deciphering the manuals. Reported-by: Xiaohan Zhang <zhangxiaohan1@huawei.com> Fixes: 79d5b4c3cd809c770d4bf9812635647016c56011 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-11-24KVM: x86: drop error recovery in em_jmp_far and em_ret_farRadim Krčmář1-25/+11
em_jmp_far and em_ret_far assumed that setting IP can only fail in 64 bit mode, but syzkaller proved otherwise (and SDM agrees). Code segment was restored upon failure, but it was left uninitialized outside of long mode, which could lead to a leak of host kernel stack. We could have fixed that by always saving and restoring the CS, but we take a simpler approach and just break any guest that manages to fail as the error recovery is error-prone and modern CPUs don't need emulator for this. Found by syzkaller: WARNING: CPU: 2 PID: 3668 at arch/x86/kvm/emulate.c:2217 em_ret_far+0x428/0x480 Kernel panic - not syncing: panic_on_warn set ... CPU: 2 PID: 3668 Comm: syz-executor Not tainted 4.9.0-rc4+ #49 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 [...] Call Trace: [...] __dump_stack lib/dump_stack.c:15 [...] dump_stack+0xb3/0x118 lib/dump_stack.c:51 [...] panic+0x1b7/0x3a3 kernel/panic.c:179 [...] __warn+0x1c4/0x1e0 kernel/panic.c:542 [...] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585 [...] em_ret_far+0x428/0x480 arch/x86/kvm/emulate.c:2217 [...] em_ret_far_imm+0x17/0x70 arch/x86/kvm/emulate.c:2227 [...] x86_emulate_insn+0x87a/0x3730 arch/x86/kvm/emulate.c:5294 [...] x86_emulate_instruction+0x520/0x1ba0 arch/x86/kvm/x86.c:5545 [...] emulate_instruction arch/x86/include/asm/kvm_host.h:1116 [...] complete_emulated_io arch/x86/kvm/x86.c:6870 [...] complete_emulated_mmio+0x4e9/0x710 arch/x86/kvm/x86.c:6934 [...] kvm_arch_vcpu_ioctl_run+0x3b7a/0x5a90 arch/x86/kvm/x86.c:6978 [...] kvm_vcpu_ioctl+0x61e/0xdd0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2557 [...] vfs_ioctl fs/ioctl.c:43 [...] do_vfs_ioctl+0x18c/0x1040 fs/ioctl.c:679 [...] SYSC_ioctl fs/ioctl.c:694 [...] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [...] entry_SYSCALL_64_fastpath+0x1f/0xc2 Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: stable@vger.kernel.org Fixes: d1442d85cc30 ("KVM: x86: Handle errors when RIP is set during far jumps") Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2016-11-02kvm: x86: Check memopp before dereference (CVE-2016-8630)Owen Hofmann1-1/+1
Commit 41061cdb98 ("KVM: emulate: do not initialize memopp") removes a check for non-NULL under incorrect assumptions. An undefined instruction with a ModR/M byte with Mod=0 and R/M-5 (e.g. 0xc7 0x15) will attempt to dereference a null pointer here. Fixes: 41061cdb98a0bec464278b4db8e894a3121671f5 Message-Id: <1477592752-126650-2-git-send-email-osh@google.com> Signed-off-by: Owen Hofmann <osh@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-07-14x86/kvm: Audit and remove any unnecessary uses of module.hPaul Gortmaker1-1/+0
Historically a lot of these existed because we did not have a distinction between what was modular code and what was providing support to modules via EXPORT_SYMBOL and friends. That changed when we forked out support for the latter into the export.h file. This means we should be able to reduce the usage of module.h in code that is obj-y Makefile or bool Kconfig. In the case of kvm where it is modular, we can extend that to also include files that are building basic support functionality but not related to loading or registering the final module; such files also have no need whatsoever for module.h The advantage in removing such instances is that module.h itself sources about 15 other headers; adding significantly to what we feed cpp, and it can obscure what headers we are effectively using. Since module.h was the source for init.h (for __init) and for export.h (for EXPORT_SYMBOL) we consider each instance for the presence of either and replace as needed. Several instances got replaced with moduleparam.h since that was really all that was required for those particular files. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kvm@vger.kernel.org Link: http://lkml.kernel.org/r/20160714001901.31603-8-paul.gortmaker@windriver.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-10x86/kvm: Add stack frame dependency to fastop() inline asmJosh Poimboeuf1-1/+5
The kbuild test robot reported this objtool warning [1]: arch/x86/kvm/emulate.o: warning: objtool: fastop()+0x69: call without frame pointer save/setup The issue seems to be caused by CONFIG_PROFILE_ALL_BRANCHES. With that option, for some reason gcc decides not to create a stack frame in fastop() before doing the inline asm call, which can result in a bad stack trace. Force a stack frame to be created if CONFIG_FRAME_POINTER is enabled by listing the stack pointer as an output operand for the inline asm statement. This change has no effect for !CONFIG_PROFILE_ALL_BRANCHES. [1] https://lists.01.org/pipermail/kbuild-all/2016-March/018249.html Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-03-21Merge branch 'core-objtool-for-linus' of ↵Linus Torvalds1-9/+22
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull 'objtool' stack frame validation from Ingo Molnar: "This tree adds a new kernel build-time object file validation feature (ONFIG_STACK_VALIDATION=y): kernel stack frame correctness validation. It was written by and is maintained by Josh Poimboeuf. The motivation: there's a category of hard to find kernel bugs, most of them in assembly code (but also occasionally in C code), that degrades the quality of kernel stack dumps/backtraces. These bugs are hard to detect at the source code level. Such bugs result in incorrect/incomplete backtraces most of time - but can also in some rare cases result in crashes or other undefined behavior. The build time correctness checking is done via the new 'objtool' user-space utility that was written for this purpose and which is hosted in the kernel repository in tools/objtool/. The tool's (very simple) UI and source code design is shaped after Git and perf and shares quite a bit of infrastructure with tools/perf (which tooling infrastructure sharing effort got merged via perf and is already upstream). Objtool follows the well-known kernel coding style. Objtool does not try to check .c or .S files, it instead analyzes the resulting .o generated machine code from first principles: it decodes the instruction stream and interprets it. (Right now objtool supports the x86-64 architecture.) From tools/objtool/Documentation/stack-validation.txt: "The kernel CONFIG_STACK_VALIDATION option enables a host tool named objtool which runs at compile time. It has a "check" subcommand which analyzes every .o file and ensures the validity of its stack metadata. It enforces a set of rules on asm code and C inline assembly code so that stack traces can be reliable. Currently it only checks frame pointer usage, but there are plans to add CFI validation for C files and CFI generation for asm files. For each function, it recursively follows all possible code paths and validates the correct frame pointer state at each instruction. It also follows code paths involving special sections, like .altinstructions, __jump_table, and __ex_table, which can add alternative execution paths to a given instruction (or set of instructions). Similarly, it knows how to follow switch statements, for which gcc sometimes uses jump tables." When this new kernel option is enabled (it's disabled by default), the tool, if it finds any suspicious assembly code pattern, outputs warnings in compiler warning format: warning: objtool: rtlwifi_rate_mapping()+0x2e7: frame pointer state mismatch warning: objtool: cik_tiling_mode_table_init()+0x6ce: call without frame pointer save/setup warning: objtool:__schedule()+0x3c0: duplicate frame pointer save warning: objtool:__schedule()+0x3fd: sibling call from callable instruction with changed frame pointer ... so that scripts that pick up compiler warnings will notice them. All known warnings triggered by the tool are fixed by the tree, most of the commits in fact prepare the kernel to be warning-free. Most of them are bugfixes or cleanups that stand on their own, but there are also some annotations of 'special' stack frames for justified cases such entries to JIT-ed code (BPF) or really special boot time code. There are two other long-term motivations behind this tool as well: - To improve the quality and reliability of kernel stack frames, so that they can be used for optimized live patching. - To create independent infrastructure to check the correctness of CFI stack frames at build time. CFI debuginfo is notoriously unreliable and we cannot use it in the kernel as-is without extra checking done both on the kernel side and on the build side. The quality of kernel stack frames matters to debuggability as well, so IMO we can merge this without having to consider the live patching or CFI debuginfo angle" * 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits) objtool: Only print one warning per function objtool: Add several performance improvements tools: Copy hashtable.h into tools directory objtool: Fix false positive warnings for functions with multiple switch statements objtool: Rename some variables and functions objtool: Remove superflous INIT_LIST_HEAD objtool: Add helper macros for traversing instructions objtool: Fix false positive warnings related to sibling calls objtool: Compile with debugging symbols objtool: Detect infinite recursion objtool: Prevent infinite recursion in noreturn detection objtool: Detect and warn if libelf is missing and don't break the build tools: Support relative directory path for 'O=' objtool: Support CROSS_COMPILE x86/asm/decoder: Use explicitly signed chars objtool: Enable stack metadata validation on 64-bit x86 objtool: Add CONFIG_STACK_VALIDATION option objtool: Add tool to perform compile-time stack metadata validation x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard sched: Always inline context_switch() ...
2016-02-24KVM: x86: fix conversion of addresses to linear in 32-bit protected modePaolo Bonzini1-2/+2
Commit e8dd2d2d641c ("Silence compiler warning in arch/x86/kvm/emulate.c", 2015-09-06) broke boot of the Hurd. The bug is that the "default:" case actually could modify "la", but after the patch this change is not reflected in *linear. The bug is visible whenever a non-zero segment base causes the linear address to wrap around the 4GB mark. Fixes: e8dd2d2d641cb2724ee10e76c0ad02e04289c017 Cc: stable@vger.kernel.org Reported-by: Aurelien Jarno <aurelien@aurel32.net> Tested-by: Aurelien Jarno <aurelien@aurel32.net> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-24x86/kvm: Make test_cc() always inlineJosh Poimboeuf1-1/+1
With some configs (including allyesconfig), gcc doesn't inline test_cc(). When that happens, test_cc() doesn't create a stack frame before inserting the inline asm call instruction. This breaks frame pointer convention if CONFIG_FRAME_POINTER is enabled and can result in a bad stack trace. Force it to always be inlined so that its containing function's stack frame can be used. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Gleb Natapov <gleb@kernel.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kvm@vger.kernel.org Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/20160122161612.GE20502@treble.redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-24x86/kvm: Set ELF function type for fastop functionsJosh Poimboeuf1-8/+21
The callable functions created with the FOP* and FASTOP* macros are missing ELF function annotations, which confuses tools like stacktool. Properly annotate them. This adds some additional labels to the assembly, but the generated binary code is unchanged (with the exception of instructions which have embedded references to __LINE__). Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Gleb Natapov <gleb@kernel.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kvm@vger.kernel.org Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/e399651c89ace54906c203c0557f66ed6ea3ce8d.1453405861.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-04KVM: x86: allow RSM from 64-bit modePaolo Bonzini1-5/+25
The SDM says that exiting system management mode from 64-bit mode is invalid, but that would be too good to be true. But actually, most of the code is already there to support exiting from compat mode (EFER.LME=1, EFER.LMA=0). Getting all the way from 64-bit mode to real mode only requires clearing CS.L and CR4.PCIDE. Cc: stable@vger.kernel.org Fixes: 660a5d517aaab9187f93854425c4c63f4a09195c Tested-by: Laszlo Ersek <lersek@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-11-04KVM: x86: handle SMBASE as physical address in RSMRadim Krčmář1-4/+3
GET_SMSTATE depends on real mode to ensure that smbase+offset is treated as a physical address, which has already caused a bug after shuffling the code. Enforce physical addressing. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Reported-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Laszlo Ersek <lersek@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-10-14KVM: x86: fix RSM into 64-bit protected modePaolo Bonzini1-3/+7
In order to get into 64-bit protected mode, you need to enable paging while EFER.LMA=1. For this to work, CS.L must be 0. Currently, we load the segments before CR0 and CR4, which means that if RSM returns into 64-bit protected mode CS.L is already 1 and everything breaks. Luckily, CS.L=0 is always the case when executing RSM, because it is forbidden to execute RSM from 64-bit protected mode. Hence it is enough to load CR0 and CR4 first, and only then the segments. Fixes: 660a5d517aaab9187f93854425c4c63f4a09195c Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-09-06Silence compiler warning in arch/x86/kvm/emulate.cValdis Kletnieks1-1/+1
Compiler warning: CC [M] arch/x86/kvm/emulate.o arch/x86/kvm/emulate.c: In function "__do_insn_fetch_bytes": arch/x86/kvm/emulate.c:814:9: warning: "linear" may be used uninitialized in this function [-Wmaybe-uninitialized] GCC is smart enough to realize that the inlined __linearize may return before setting the value of linear, but not smart enough to realize the same X86EMU_CONTINUE blocks actual use of the value. However, the value of 'linear' can only be set to one value, so hoisting the one line of code upwards makes GCC happy with the code. Reported-by: Aruna Hewapathirane <aruna.hewapathirane@gmail.com> Tested-by: Aruna Hewapathirane <aruna.hewapathirane@gmail.com> Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-06-04KVM: x86: save/load state on SMM switchPaolo Bonzini1-1/+247
The big ugly one. This patch adds support for switching in and out of system management mode, respectively upon receiving KVM_REQ_SMI and upon executing a RSM instruction. Both 32- and 64-bit formats are supported for the SMM state save area. Reviewed-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-06-04KVM: x86: stubs for SMM supportPaolo Bonzini1-1/+9
This patch adds the interface between x86.c and the emulator: the SMBASE register, a new emulator flag, the RSM instruction. It also adds a new request bit that will be used by the KVM_SMI ioctl. Reviewed-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-06-04KVM: x86: pass the whole hflags field to emulator and backPaolo Bonzini1-3/+3
The hflags field will contain information about system management mode and will be useful for the emulator. Pass the entire field rather than just the guest-mode information. Reviewed-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-05-19KVM: x86: Fix zero iterations REP-stringNadav Amit1-0/+25
When a REP-string is executed in 64-bit mode with an address-size prefix, ECX/EDI/ESI are used as counter and pointers. When ECX is initially zero, Intel CPUs clear the high 32-bits of RCX, and recent Intel CPUs update the high bits of the pointers in MOVS/STOS. This behavior is specific to Intel according to few experiments. As one may guess, this is an undocumented behavior. Yet, it is observable in the guest, since at least VMX traps REP-INS/OUTS even when ECX=0. Note that VMware appears to get it right. The behavior can be observed using the following code: #include <stdio.h> #define LOW_MASK (0xffffffff00000000ull) #define ALL_MASK (0xffffffffffffffffull) #define TEST(opcode) \ do { \ asm volatile(".byte 0xf2 \n\t .byte 0x67 \n\t .byte " opcode "\n\t" \ : "=S"(s), "=c"(c), "=D"(d) \ : "S"(ALL_MASK), "c"(LOW_MASK), "D"(ALL_MASK)); \ printf("opcode %s rcx=%llx rsi=%llx rdi=%llx\n", \ opcode, c, s, d); \ } while(0) void main() { unsigned long long s, d, c; iopl(3); TEST("0x6c"); TEST("0x6d"); TEST("0x6e"); TEST("0x6f"); TEST("0xa4"); TEST("0xa5"); TEST("0xa6"); TEST("0xa7"); TEST("0xaa"); TEST("0xab"); TEST("0xae"); TEST("0xaf"); } Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-05-19KVM: x86: Fix update RCX/RDI/RSI on REP-stringNadav Amit1-6/+2
When REP-string instruction is preceded with an address-size prefix, ECX/EDI/ESI are used as the operation counter and pointers. When they are updated, the high 32-bits of RCX/RDI/RSI are cleared, similarly to the way they are updated on every 32-bit register operation. Fix it. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-05-19KVM: x86: Fix DR7 mask on task-switch while debuggingNadav Amit1-1/+5
If the host sets hardware breakpoints to debug the guest, and a task-switch occurs in the guest, the architectural DR7 will not be updated. The effective DR7 would be updated instead. This fix puts the DR7 update during task-switch emulation, so it now uses the standard DR setting mechanism instead of the one that was previously used. As a bonus, the update of DR7 will now be effective for AMD as well. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-05-08KVM: x86: Call-far should not be emulated as stack opNadav Amit1-1/+1
Far call in 64-bit has a 32-bit operand size. Remove the marking of this operation as Stack so it can be emulated correctly in 64-bit. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-04-08kvm: x86: fix x86 eflags fixed bitWanpeng Li1-3/+3
Guest can't be booted w/ ept=0, there is a message dumped as below: If you're running a guest on an Intel machine without unrestricted mode support, the failure can be most likely due to the guest entering an invalid state for Intel VT. For example, the guest maybe running in big real mode which is not supported on less recent Intel processors. EAX=00000011 EBX=f000d2f6 ECX=00006cac EDX=000f8956 ESI=bffbdf62 EDI=00000000 EBP=00006c68 ESP=00006c68 EIP=0000d187 EFL=00000004 [-----P-] CPL=0 II=0 A20=1 SMM=0 HLT=0 ES =e000 000e0000 ffffffff 00809300 DPL=0 DS16 [-WA] CS =f000 000f0000 ffffffff 00809b00 DPL=0 CS16 [-RA] SS =0000 00000000 ffffffff 00809300 DPL=0 DS16 [-WA] DS =0000 00000000 ffffffff 00809300 DPL=0 DS16 [-WA] FS =0000 00000000 ffffffff 00809300 DPL=0 DS16 [-WA] GS =0000 00000000 ffffffff 00809300 DPL=0 DS16 [-WA] LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy GDT= 000f6a80 00000037 IDT= 000f6abe 00000000 CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000 DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 DR6=00000000ffff0ff0 DR7=0000000000000400 EFER=0000000000000000 Code=01 1e b8 6a 2e 0f 01 16 74 6a 0f 20 c0 66 83 c8 01 0f 22 c0 <66> ea 8f d1 0f 00 08 00 b8 10 00 00 00 8e d8 8e c0 8e d0 8e e0 8e e8 89 c8 ff e2 89 c1 b8X X86 eflags bit 1 is fixed set, which means that 1 << 1 is set instead of 1, this patch fix it. Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com> Message-Id: <1428473294-6633-1-git-send-email-wanpeng.li@linux.intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-30KVM: remove useless check of "ret" variable prior to returning the same valueEugene Korenevsky1-3/+1
A trivial code cleanup. This `if` is redundant. Signed-off-by: Eugene Korenevsky <ekorenevsky@gmail.com> Message-Id: <20150328222717.GA6508@gnote> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-30KVM: x86: Remove redundant definitionsNadav Amit1-3/+3
Some constants are redfined in emulate.c. Avoid it. s/SELECTOR_RPL_MASK/SEGMENT_RPL_MASK s/SELECTOR_TI_MASK/SEGMENT_TI_MASK No functional change. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Message-Id: <1427635984-8113-3-git-send-email-namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-30KVM: x86: removing redundant eflags bits definitionsNadav Amit1-59/+46
The eflags are redefined (using other defines) in emulate.c. Use the definition from processor-flags.h as some mess already started. No functional change. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Message-Id: <1427635984-8113-2-git-send-email-namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-30KVM: x86: BSF and BSR emulation change register unnecassarilyNadav Amit1-1/+18
If the source of BSF and BSR is zero, the destination register should not change. That is how real hardware behaves. If we set the destination even with the same value that we had before, we may clear bits [63:32] unnecassarily. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Message-Id: <1427719163-5429-4-git-send-email-namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-30KVM: x86: POPA emulation may not clear bits [63:32]Nadav Amit1-16/+23
POPA should assign the values to the registers as usual registers are assigned. In other words, 32-bits register assignments should clear bits [63:32] of the register. Split the code of register assignments that will be used by future changes as well. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Message-Id: <1427719163-5429-3-git-send-email-namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-30KVM: x86: CMOV emulation on legacy mode is wrongNadav Amit1-2/+1
On legacy mode CMOV emulation should still clear bits [63:32] even if the assignment is not done. The previous fix 140bad89fd ("KVM: x86: emulation of dword cmov on long-mode should clear [63:32]") was incomplete. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Message-Id: <1427719163-5429-2-git-send-email-namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-13KVM: x86: Fix re-execution of patched vmmcallJan Kiszka1-14/+3
For a very long time (since 2b3d2a20), the path handling a vmmcall instruction of the guest on an Intel host only applied the patch but no longer handled the hypercall. The reverse case, vmcall on AMD hosts, is fine. As both em_vmcall and em_vmmcall actually have to do the same, we can fix the issue by consolidating both into the same handler. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2015-02-24KVM: emulate: fix CMPXCHG8B on 32-bit hostsPaolo Bonzini1-1/+2
This has been broken for a long time: it broke first in 2.6.35, then was almost fixed in 2.6.36 but this one-liner slipped through the cracks. The bug shows up as an infinite loop in Windows 7 (and newer) boot on 32-bit hosts without EPT. Windows uses CMPXCHG8B to write to page tables, which causes a page fault if running without EPT; the emulator is then called from kvm_mmu_page_fault. The loop then happens if the higher 4 bytes are not 0; the common case for this is that the NX bit (bit 63) is 1. Fixes: 6550e1f165f384f3a46b60a1be9aba4bc3c2adad Fixes: 16518d5ada690643453eb0aef3cc7841d3623c2d Cc: stable@vger.kernel.org # 2.6.35+ Reported-by: Erik Rull <erik.rull@rdsoftware.de> Tested-by: Erik Rull <erik.rull@rdsoftware.de> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-02-13Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds1-74/+156
Pull KVM update from Paolo Bonzini: "Fairly small update, but there are some interesting new features. Common: Optional support for adding a small amount of polling on each HLT instruction executed in the guest (or equivalent for other architectures). This can improve latency up to 50% on some scenarios (e.g. O_DSYNC writes or TCP_RR netperf tests). This also has to be enabled manually for now, but the plan is to auto-tune this in the future. ARM/ARM64: The highlights are support for GICv3 emulation and dirty page tracking s390: Several optimizations and bugfixes. Also a first: a feature exposed by KVM (UUID and long guest name in /proc/sysinfo) before it is available in IBM's hypervisor! :) MIPS: Bugfixes. x86: Support for PML (page modification logging, a new feature in Broadwell Xeons that speeds up dirty page tracking), nested virtualization improvements (nested APICv---a nice optimization), usual round of emulation fixes. There is also a new option to reduce latency of the TSC deadline timer in the guest; this needs to be tuned manually. Some commits are common between this pull and Catalin's; I see you have already included his tree. Powerpc: Nothing yet. The KVM/PPC changes will come in through the PPC maintainers, because I haven't received them yet and I might end up being offline for some part of next week" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (130 commits) KVM: ia64: drop kvm.h from installed user headers KVM: x86: fix build with !CONFIG_SMP KVM: x86: emulate: correct page fault error code for NoWrite instructions KVM: Disable compat ioctl for s390 KVM: s390: add cpu model support KVM: s390: use facilities and cpu_id per KVM KVM: s390/CPACF: Choose crypto control block format s390/kernel: Update /proc/sysinfo file with Extended Name and UUID KVM: s390: reenable LPP facility KVM: s390: floating irqs: fix user triggerable endless loop kvm: add halt_poll_ns module parameter kvm: remove KVM_MMIO_SIZE KVM: MIPS: Don't leak FPU/DSP to guest KVM: MIPS: Disable HTW while in guest KVM: nVMX: Enable nested posted interrupt processing KVM: nVMX: Enable nested virtual interrupt delivery KVM: nVMX: Enable nested apic register virtualization KVM: nVMX: Make nested control MSRs per-cpu KVM: nVMX: Enable nested virtualize x2apic mode KVM: nVMX: Prepare for using hardware MSR bitmap ...
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