- 08 Mar, 2012 21 commits
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Takuya Yoshikawa authored
Other threads may process the same page in that small window and skip TLB flush and then return before these functions do flush. Signed-off-by:
Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> Signed-off-by:
Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by:
Avi Kivity <avi@redhat.com>
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Takuya Yoshikawa authored
Some members of kvm_memory_slot are not used by every architecture. This patch is the first step to make this difference clear by introducing kvm_memory_slot::arch; lpage_info is moved into it. Signed-off-by:
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Takuya Yoshikawa authored
Narrow down the controlled text inside the conditional so that it will include lpage_info and rmap stuff only. For this we change the way we check whether the slot is being created from "if (npages && !new.rmap)" to "if (npages && !old.npages)". We also stop checking if lpage_info is NULL when we create lpage_info because we do it from inside the slot creation code block. Signed-off-by:
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Takuya Yoshikawa authored
This makes it easy to make lpage_info architecture specific. Signed-off-by:
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Takuya Yoshikawa authored
This patch cleans up the code and removes the "(void)level;" warning suppressor. Note that we can also use this for PT_PAGE_TABLE_LEVEL to treat every level uniformly later. Signed-off-by:
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Christian Borntraeger authored
There are several cases were we need the control registers for userspace. Lets also provide those in kvm_run. Signed-off-by:
Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by:
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Jens Freimann authored
When we do a stop and store status we need to pass ACTION_STOP_ON_STOP flag to __sigp_stop(). Signed-off-by:
Jens Freimann <jfrei@linux.vnet.ibm.com> Signed-off-by:
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Jens Freimann authored
In __inject_sigp_stop() do nothing when the CPU is already in stopped state. Signed-off-by:
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Jens Freimann authored
On reboot the guest sends in smp_send_stop() a sigp stop to all CPUs except for current CPU. Then the guest switches to the IPL cpu by sending a restart to the IPL CPU, followed by a sigp stop to the current cpu. Since restart is handled by userspace it's possible that the restart is delivered before the old stop. This means that the IPL CPU isn't restarted and we have no running CPUs. So let's make sure that there is no stop action pending when we do the restart. Signed-off-by:
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Jens Freimann authored
In handle_stop() handle the stop bit before doing the store status as described for "Stop and Store Status" in the Principles of Operation. We have to give up the local_int.lock before calling kvm store status since it calls gmap_fault() which might sleep. Since local_int.lock only protects local_int.* and not guest memory we can give up the lock. Signed-off-by:
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Christian Borntraeger authored
commit 7eef87dc (KVM: s390: fix register setting) added a load of the floating point control register to the KVM_SET_FPU path. Lets make sure that the fpc is valid. Signed-off-by:
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Takuya Yoshikawa authored
This patch fixes a race introduced by: commit 95d4c16c KVM: Optimize dirty logging by rmap_write_protect() During protecting pages for dirty logging, other threads may also try to protect a page in mmu_sync_children() or kvm_mmu_get_page(). In such a case, because get_dirty_log releases mmu_lock before flushing TLB's, the following race condition can happen: A (get_dirty_log) B (another thread) lock(mmu_lock) clear pte.w unlock(mmu_lock) lock(mmu_lock) pte.w is already cleared unlock(mmu_lock) skip TLB flush return ... TLB flush Though thread B assumes the page has already been protected when it returns, the remaining TLB entry will break that assumption. This patch fixes this problem by making get_dirty_log hold the mmu_lock until it flushes the TLB's. Signed-off-by:
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Raghavendra K T authored
yield_on_hlt was introduced for CPU bandwidth capping. Now it is redundant with CFS hardlimit. yield_on_hlt also complicates the scenario in paravirtual environment, that needs to trap halt. for e.g. paravirtualized ticket spinlocks. Acked-by:
Anthony Liguori <aliguori@us.ibm.com> Signed-off-by:
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Signed-off-by:
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Zachary Amsden authored
This allows us to track the original nanosecond and counter values at each phase of TSC writing by the guest. This gets us perfect offset matching for stable TSC systems, and perfect software computed TSC matching for machines with unstable TSC. Signed-off-by:
Zachary Amsden <zamsden@gmail.com> Signed-off-by:
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Zachary Amsden authored
During a host suspend, TSC may go backwards, which KVM interprets as an unstable TSC. Technically, KVM should not be marking the TSC unstable, which causes the TSC clocksource to go bad, but we need to be adjusting the TSC offsets in such a case. Dealing with this issue is a little tricky as the only place we can reliably do it is before much of the timekeeping infrastructure is up and running. On top of this, we are not in a KVM thread context, so we may not be able to safely access VCPU fields. Instead, we compute our best known hardware offset at power-up and stash it to be applied to all VCPUs when they actually start running. Signed-off-by:
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Marcelo Tosatti authored
Redefine the API to take a parameter indicating whether an adjustment is in host or guest cycles. Signed-off-by:
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Zachary Amsden authored
The variable last_host_tsc was removed from upstream code. I am adding it back for two reasons. First, it is unnecessary to use guest TSC computation to conclude information about the host TSC. The guest may set the TSC backwards (this case handled by the previous patch), but the computation of guest TSC (and fetching an MSR) is significanlty more work and complexity than simply reading the hardware counter. In addition, we don't actually need the guest TSC for any part of the computation, by always recomputing the offset, we can eliminate the need to deal with the current offset and any scaling factors that may apply. The second reason is that later on, we are going to be using the host TSC value to restore TSC offsets after a host S4 suspend, so we need to be reading the host values, not the guest values here. Signed-off-by:
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Zachary Amsden authored
The variable last_guest_tsc was being used as an ad-hoc indicator that guest TSC has been initialized and recorded correctly. However, it may not have been, it could be that guest TSC has been set to some large value, the back to a small value (by, say, a software reboot). This defeats the logic and causes KVM to falsely assume that the guest TSC has gone backwards, marking the host TSC unstable, which is undesirable behavior. In addition, rather than try to compute an offset adjustment for the TSC on unstable platforms, just recompute the whole offset. This allows us to get rid of one callsite for adjust_tsc_offset, which is problematic because the units it takes are in guest units, but here, the computation was originally being done in host units. Doing this, and also recording last_guest_tsc when the TSC is written allow us to remove the tricky logic which depended on last_guest_tsc being zero to indicate a reset of uninitialized value. Instead, we now have the guarantee that the guest TSC offset is always at least something which will get us last_guest_tsc. Signed-off-by:
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Zachary Amsden authored
Currently, when the TSC is written by the guest, the variable ns is updated to force the current write to appear to have taken place at the time of the first write in this sync phase. This leaves a cliff at the end of the match window where updates will fall of the end. There are two scenarios where this can be a problem in practe - first, on a system with a large number of VCPUs, the sync period may last for an extended period of time. The second way this can happen is if the VM reboots very rapidly and we catch a VCPU TSC synchronization just around the edge. We may be unaware of the reboot, and thus the first VCPU might synchronize with an old set of the timer (at, say 0.97 seconds ago, when first powered on). The second VCPU can come in 0.04 seconds later to try to synchronize, but it misses the window because it is just over the threshold. Instead, stop doing this artificial setback of the ns variable and just update it with every write of the TSC. It may be observed that doing so causes values computed by compute_guest_tsc to diverge slightly across CPUs - note that the last_tsc_ns and last_tsc_write variable are used here, and now they last_tsc_ns will be different for each VCPU, reflecting the actual time of the update. However, compute_guest_tsc is used only for guests which already have TSC stability issues, and further, note that the previous patch has caused last_tsc_write to be incremented by the difference in nanoseconds, converted back into guest cycles. As such, only boundary rounding errors should be visible, which given the resolution in nanoseconds, is going to only be a few cycles and only visible in cross-CPU consistency tests. The problem can be fixed by adding a new set of variables to track the start offset and start write value for the current sync cycle. Signed-off-by:
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Zachary Amsden authored
There are a few improvements that can be made to the TSC offset matching code. First, we don't need to call the 128-bit multiply (especially on a constant number), the code works much nicer to do computation in nanosecond units. Second, the way everything is setup with software TSC rate scaling, we currently have per-cpu rates. Obviously this isn't too desirable to use in practice, but if for some reason we do change the rate of all VCPUs at runtime, then reset the TSCs, we will only want to match offsets for VCPUs running at the same rate. Finally, for the case where we have an unstable host TSC, but rate scaling is being done in hardware, we should call the platform code to compute the TSC offset, so the math is reorganized to recompute the base instead, then transform the base into an offset using the existing API. [avi: fix 64-bit division on i386] Signed-off-by:
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Zachary Amsden authored
This requires some restructuring; rather than use 'virtual_tsc_khz' to indicate whether hardware rate scaling is in effect, we consider each VCPU to always have a virtual TSC rate. Instead, there is new logic above the vendor-specific hardware scaling that decides whether it is even necessary to use and updates all rate variables used by common code. This means we can simply query the virtual rate at any point, which is needed for software rate scaling. There is also now a threshold added to the TSC rate scaling; minor differences and variations of measured TSC rate can accidentally provoke rate scaling to be used when it is not needed. Instead, we have a tolerance variable called tsc_tolerance_ppm, which is the maximum variation from user requested rate at which scaling will be used. The default is 250ppm, which is the half the threshold for NTP adjustment, allowing for some hardware variation. In the event that hardware rate scaling is not available, we can kludge a bit by forcing TSC catchup to turn on when a faster than hardware speed has been requested, but there is nothing available yet for the reverse case; this requires a trap and emulate software implementation for RDTSC, which is still forthcoming. [avi: fix 64-bit division on i386] Signed-off-by:
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- 05 Mar, 2012 19 commits
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Marcelo Tosatti authored
Increase recommended max vcpus from 64 to 160 (tested internally at Red Hat). Signed-off-by:
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Igor Mammedov authored
When kvm guest uses kvmclock, it may hang on vcpu hot-plug. This is caused by an overflow in pvclock_get_nsec_offset, u64 delta = tsc - shadow->tsc_timestamp; which in turn is caused by an undefined values from percpu hv_clock that hasn't been initialized yet. Uninitialized clock on being booted cpu is accessed from start_secondary -> smp_callin -> smp_store_cpu_info -> identify_secondary_cpu -> mtrr_ap_init -> mtrr_restore -> stop_machine_from_inactive_cpu -> queue_stop_cpus_work ... -> sched_clock -> kvm_clock_read which is well before x86_cpuinit.setup_percpu_clockev call in start_secondary, where percpu clock is initialized. This patch introduces a hook that allows to setup/initialize per_cpu clock early and avoid overflow due to reading - undefined values - old values if cpu was offlined and then onlined again Another possible early user of this clock source is ftrace that accesses it to get timestamps for ring buffer entries. So if mtrr_ap_init is moved from identify_secondary_cpu to past x86_cpuinit.setup_percpu_clockev in start_secondary, ftrace may cause the same overflow/hang on cpu hot-plug anyway. More complete description of the problem: https://lkml.org/lkml/2012/2/2/101 Credits to Marcelo Tosatti <mtosatti@redhat.com> for hook idea. Acked-by:Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
Igor Mammedov <imammedo@redhat.com> Signed-off-by:
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Gleb Natapov authored
The spec says that during initialization "The edge sense circuit is reset which means that following initialization an interrupt request (IR) input must make a low-to-high transition to generate an interrupt", but currently if edge triggered interrupt is in IRR it is delivered after i8259 initialization. Signed-off-by:
Gleb Natapov <gleb@redhat.com> Signed-off-by:
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Alexander Graf authored
We're currently allocating 16MB of linear memory on demand when creating a guest. That does work some times, but finding 16MB of linear memory available in the system at runtime is definitely not a given. So let's add another command line option similar to the RMA preallocator, that we can use to keep a pool of page tables around. Now, when a guest gets created it has a pretty low chance of receiving an OOM. Signed-off-by:
Alexander Graf <agraf@suse.de> Signed-off-by:
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Alexander Graf authored
RMAs and HPT preallocated spaces should be zeroed, so we don't accidently leak information from previous VM executions. Signed-off-by:
Paul Mackerras <paulus@samba.org> Signed-off-by:
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Alexander Graf authored
We have code to allocate big chunks of linear memory on bootup for later use. This code is currently used for RMA allocation, but can be useful beyond that extent. Make it generic so we can reuse it for other stuff later. Signed-off-by:
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Alexander Graf authored
When enabling the current KVM code on e500mc, I get the following oops: Oops: Exception in kernel mode, sig: 4 [#1] SMP NR_CPUS=8 P2041 RDB Modules linked in: NIP: c067df4c LR: c067df44 CTR: 00000000 REGS: ee055ed0 TRAP: 0700 Not tainted (3.2.0-10391-g36c5afe) MSR: 00029002 <CE,EE,ME> CR: 24042022 XER: 00000000 TASK = ee0429b0[1] 'swapper/0' THREAD: ee054000 CPU: 2 GPR00: c067df44 ee055f80 ee0429b0 00000000 00000058 0000003f ee211600 60c6b864 GPR08: 7cc903a6 0000002c 00000000 00000001 44042082 2d180088 00000000 00000000 GPR16: c0000a00 00000014 3fffffff 03fe9000 00000015 7ff3be68 c06e0000 00000000 GPR24: 00000000 00000000 00001720 c067df1c c06e0000 00000000 ee054000 c06ab51c NIP [c067df4c] kvmppc_e500_init+0x30/0xf8 LR [c067df44] kvmppc_e500_init+0x28/0xf8 Call Trace: [ee055f80] [c067df44] kvmppc_e500_init+0x28/0xf8 (unreliable) [ee055fb0] [c0001d30] do_one_initcall+0x50/0x1f0 [ee055fe0] [c06721dc] kernel_init+0xa4/0x14c [ee055ff0] [c000e910] kernel_thread+0x4c/0x68 Instruction dump: 9421ffd0 7c0802a6 93410018 9361001c 90010034 93810020 93a10024 93c10028 93e1002c 4bfffe7d 2c030000 408200a4 <7c1082a6> 90010008 7c1182a6 9001000c ---[ end trace b8ef4903fcbf9dd3 ]--- Since it doesn't make sense to run the init function on any non-supported platform, we can just call our "is this platform supported?" function and bail out of init() if it's not. Signed-off-by: -
Paul Mackerras authored
This moves __gfn_to_memslot() and search_memslots() from kvm_main.c to kvm_host.h to reduce the code duplication caused by the need for non-modular code in arch/powerpc/kvm/book3s_hv_rm_mmu.c to call gfn_to_memslot() in real mode. Rather than putting gfn_to_memslot() itself in a header, which would lead to increased code size, this puts __gfn_to_memslot() in a header. Then, the non-modular uses of gfn_to_memslot() are changed to call __gfn_to_memslot() instead. This way there is only one place in the source code that needs to be changed should the gfn_to_memslot() implementation need to be modified. On powerpc, the Book3S HV style of KVM has code that is called from real mode which needs to call gfn_to_memslot() and thus needs this. (Module code is allocated in the vmalloc region, which can't be accessed in real mode.) With this, we can remove builtin_gfn_to_memslot() from book3s_hv_rm_mmu.c. Signed-off-by:
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Avi Kivity authored
If the guest thinks it's an AMD, it will not have prepared the SYSENTER MSRs, and if the guest executes SYSENTER in compatibility mode, it will fails. Detect this condition and #UD instead, like the spec says. Signed-off-by: -
Julian Stecklina authored
If the guest programs an IPI with level=0 (de-assert) and trig_mode=0 (edge), it is erroneously treated as INIT de-assert and ignored, but to quote the spec: "For this delivery mode [INIT de-assert], the level flag must be set to 0 and trigger mode flag to 1." Signed-off-by:
Julian Stecklina <js@alien8.de> Signed-off-by:
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Michael S. Tsirkin authored
find_index_from_host_irq returns 0 on error but callers assume < 0 on error. This should not matter much: an out of range irq should never happen since irq handler was registered with this irq #, and even if it does we get a spurious msix irq in guest and typically nothing terrible happens. Still, better to make it consistent. Signed-off-by:
Michael S. Tsirkin <mst@redhat.com> Signed-off-by:
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Davidlohr Bueso authored
Also use true instead of 1 for enabling by default. Signed-off-by:
Davidlohr Bueso <dave@gnu.org> Signed-off-by:
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Takuya Yoshikawa authored
Signed-off-by:
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Takuya Yoshikawa authored
Signed-off-by:
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Takuya Yoshikawa authored
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Avi Kivity authored
Currently we treat MOVSX/MOVZX with a byte source as a byte instruction, and change the destination operand size with a hack. Change it to be a word instruction, so the destination receives its natural size, and change the source to be SrcMem8. Signed-off-by:
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Avi Kivity authored
Useful for MOVSX/MOVZX. Signed-off-by:
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Scott Wood authored
Instead of keeping separate copies of struct kvm_vcpu_arch_shared (one in the code, one in the docs) that inevitably fail to be kept in sync (already sr[] is missing from the doc version), just point to the header file as the source of documentation on the contents of the magic page. Signed-off-by:
Scott Wood <scottwood@freescale.com> Acked-by:
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Alexander Graf authored
We need the KVM_REG namespace for generic register settings now, so let's rename the existing users to something different, enabling us to reuse the namespace for more visible interfaces. While at it, also move these private constants to a private header. Signed-off-by:
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