- 14 Dec, 2020 5 commits
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Tom Lendacky authored
Update the GHCB accessor functions to add functions for retrieve GHCB fields by name. Update existing code to use the new accessor functions. Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Message-Id: <664172c53a5fb4959914e1a45d88e805649af0ad.1607620209.git.thomas.lendacky@amd.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Tom Lendacky authored
Add support to KVM for determining if a system is capable of supporting SEV-ES as well as determining if a guest is an SEV-ES guest. Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Message-Id: <e66792323982c822350e40c7a1cf67ea2978a70b.1607620209.git.thomas.lendacky@amd.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Tom Lendacky authored
When both KVM support and the CCP driver are built into the kernel instead of as modules, KVM initialization can happen before CCP initialization. As a result, sev_platform_status() will return a failure when it is called from sev_hardware_setup(), when this isn't really an error condition. Since sev_platform_status() doesn't need to be called at this time anyway, remove the invocation from sev_hardware_setup(). Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Message-Id: <618380488358b56af558f2682203786f09a49483.1607620209.git.thomas.lendacky@amd.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Tom Lendacky authored
On systems that do not have hardware enforced cache coherency between encrypted and unencrypted mappings of the same physical page, the hypervisor can use the VM page flush MSR (0xc001011e) to flush the cache contents of an SEV guest page. When a small number of pages are being flushed, this can be used in place of issuing a WBINVD across all CPUs. CPUID 0x8000001f_eax[2] is used to determine if the VM page flush MSR is available. Add a CPUID feature to indicate it is supported and define the MSR. Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Message-Id: <f1966379e31f9b208db5257509c4a089a87d33d0.1607620209.git.thomas.lendacky@amd.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Uros Bizjak authored
Move kvm_machine_check to x86.h to avoid two exact copies of the same function in kvm.c and svm.c. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Message-Id: <20201029135600.122392-1-ubizjak@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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- 12 Dec, 2020 7 commits
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Paolo Bonzini authored
Merge tag 'kvm-s390-next-5.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD KVM: s390: Features and Test for 5.11 - memcg accouting for s390 specific parts of kvm and gmap - selftest for diag318 - new kvm_stat for when async_pf falls back to sync The selftest even triggers a non-critical bug that is unrelated to diag318, fix will follow later.
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Paolo Bonzini authored
Until commit e7c587da ("x86/speculation: Use synthetic bits for IBRS/IBPB/STIBP"), KVM was testing both Intel and AMD CPUID bits before allowing the guest to write MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD. Testing only Intel bits on VMX processors, or only AMD bits on SVM processors, fails if the guests are created with the "opposite" vendor as the host. While at it, also tweak the host CPU check to use the vendor-agnostic feature bit X86_FEATURE_IBPB, since we only care about the availability of the MSR on the host here and not about specific CPUID bits. Fixes: e7c587da ("x86/speculation: Use synthetic bits for IBRS/IBPB/STIBP") Cc: stable@vger.kernel.org Reported-by: Denis V. Lunev <den@openvz.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Cathy Zhang authored
AVX512_FP16 is supported by Intel processors, like Sapphire Rapids. It could gain better performance for it's faster compared to FP32 if the precision or magnitude requirements are met. It's availability is indicated by CPUID.(EAX=7,ECX=0):EDX[bit 23]. Expose it in KVM supported CPUID, then guest could make use of it; no new registers are used, only new instructions. Signed-off-by: Cathy Zhang <cathy.zhang@intel.com> Signed-off-by: Kyung Min Park <kyung.min.park@intel.com> Acked-by: Dave Hansen <dave.hansen@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Message-Id: <20201208033441.28207-3-kyung.min.park@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Kyung Min Park authored
Enumerate AVX512 Half-precision floating point (FP16) CPUID feature flag. Compared with using FP32, using FP16 cut the number of bits required for storage in half, reducing the exponent from 8 bits to 5, and the mantissa from 23 bits to 10. Using FP16 also enables developers to train and run inference on deep learning models fast when all precision or magnitude (FP32) is not needed. A processor supports AVX512 FP16 if CPUID.(EAX=7,ECX=0):EDX[bit 23] is present. The AVX512 FP16 requires AVX512BW feature be implemented since the instructions for manipulating 32bit masks are associated with AVX512BW. The only in-kernel usage of this is kvm passthrough. The CPU feature flag is shown as "avx512_fp16" in /proc/cpuinfo. Signed-off-by: Kyung Min Park <kyung.min.park@intel.com> Acked-by: Dave Hansen <dave.hansen@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Message-Id: <20201208033441.28207-2-kyung.min.park@intel.com> Acked-by: Borislav Petkov <bp@suse.de> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Aaron Lewis authored
Both user_msr_test and userspace_msr_exit_test tests the functionality of kvm_msr_filter. Instead of testing this feature in two tests, merge them together, so there is only one test for this feature. Signed-off-by: Aaron Lewis <aaronlewis@google.com> Message-Id: <20201204172530.2958493-1-aaronlewis@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Aaron Lewis authored
Add a selftest to test that when the ioctl KVM_X86_SET_MSR_FILTER is called with an MSR list, those MSRs exit to userspace. This test uses 3 MSRs to test this: 1. MSR_IA32_XSS, an MSR the kernel knows about. 2. MSR_IA32_FLUSH_CMD, an MSR the kernel does not know about. 3. MSR_NON_EXISTENT, an MSR invented in this test for the purposes of passing a fake MSR from the guest to userspace. KVM just acts as a pass through. Userspace is also able to inject a #GP. This is demonstrated when MSR_IA32_XSS and MSR_IA32_FLUSH_CMD are misused in the test. When this happens a #GP is initiated in userspace to be thrown in the guest which is handled gracefully by the exception handling framework introduced earlier in this series. Tests for the generic instruction emulator were also added. For this to work the module parameter kvm.force_emulation_prefix=1 has to be enabled. If it isn't enabled the tests will be skipped. A test was also added to ensure the MSR permission bitmap is being set correctly by executing reads and writes of MSR_FS_BASE and MSR_GS_BASE in the guest while alternating which MSR userspace should intercept. If the permission bitmap is being set correctly only one of the MSRs should be coming through at a time, and the guest should be able to read and write the other one directly. Signed-off-by: Aaron Lewis <aaronlewis@google.com> Reviewed-by: Alexander Graf <graf@amazon.com> Message-Id: <20201012194716.3950330-5-aaronlewis@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Uros Bizjak authored
Saves one byte in __vmx_vcpu_run for the same functionality. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Message-Id: <20201029140457.126965-1-ubizjak@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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- 10 Dec, 2020 4 commits
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Christian Borntraeger authored
Right now we do count pfault (pseudo page faults aka async page faults start and completion events). What we do not count is, if an async page fault would have been possible by the host, but it was disabled by the guest (e.g. interrupts off, pfault disabled, secure execution....). Let us count those as well in the pfault_sync counter. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Cornelia Huck <cohuck@redhat.com> Link: https://lore.kernel.org/r/20201125090658.38463-1-borntraeger@de.ibm.com
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Collin Walling authored
The DIAGNOSE 0x0318 instruction, unique to s390x, is a privileged call that must be intercepted via SIE, handled in userspace, and the information set by the instruction is communicated back to KVM. To test the instruction interception, an ad-hoc handler is defined which simply has a VM execute the instruction and then userspace will extract the necessary info. The handler is defined such that the instruction invocation occurs only once. It is up to the caller to determine how the info returned by this handler should be used. The diag318 info is communicated from userspace to KVM via a sync_regs call. This is tested during a sync_regs test, where the diag318 info is requested via the handler, then the info is stored in the appropriate register in KVM via a sync registers call. If KVM does not support diag318, then the tests will print a message stating that diag318 was skipped, and the asserts will simply test against a value of 0. Signed-off-by: Collin Walling <walling@linux.ibm.com> Link: https://lore.kernel.org/r/20201207154125.10322-1-walling@linux.ibm.comAcked-by: Janosch Frank <frankja@linux.ibm.com> Acked-by: Cornelia Huck <cohuck@redhat.com> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
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Christian Borntraeger authored
gmap allocations can be attributed to a process. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Heiko Carstens <hca@linux.ibm.com> Acked-by: Janosch Frank <frankja@linux.ibm.com> Acked-by: Cornelia Huck <cohuck@redhat.com>
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Christian Borntraeger authored
Almost all kvm allocations in the s390x KVM code can be attributed to the process that triggers the allocation (in other words, no global allocation for other guests). This will help the memcg controller to make the right decisions. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Janosch Frank <frankja@linux.ibm.com> Acked-by: Cornelia Huck <cohuck@redhat.com>
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- 09 Dec, 2020 1 commit
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Maxim Levitsky authored
In the commit 1c96dcce ("KVM: x86: fix apic_accept_events vs check_nested_events"), we accidently started latching SIPIs that are received while the cpu is not waiting for them. This causes vCPUs to never enter a halted state. Fixes: 1c96dcce ("KVM: x86: fix apic_accept_events vs check_nested_events") Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20201203143319.159394-2-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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- 03 Dec, 2020 1 commit
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Paolo Bonzini authored
Since the ASID is now stored in svm->asid, pre_sev_run should also place it there and not directly in the VMCB control area. Reported-by: Ashish Kalra <Ashish.Kalra@amd.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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- 27 Nov, 2020 1 commit
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Paolo Bonzini authored
SVM generally ignores fixed-1 bits. Set them manually so that we do not end up by mistake without those bits set in struct kvm_vcpu; it is part of userspace API that KVM always returns value with the bits set. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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- 19 Nov, 2020 2 commits
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Ben Gardon authored
Add an extremely verbose trace point to the TDP MMU to log all SPTE changes, regardless of callstack / motivation. This is useful when a complete picture of the paging structure is needed or a change cannot be explained with the other, existing trace points. Tested: ran the demand paging selftest on an Intel Skylake machine with all the trace points used by the TDP MMU enabled and observed them firing with expected values. This patch can be viewed in Gerrit at: https://linux-review.googlesource.com/c/virt/kvm/kvm/+/3813Signed-off-by: Ben Gardon <bgardon@google.com> Message-Id: <20201027175944.1183301-2-bgardon@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Ben Gardon authored
The TDP MMU was initially implemented without some of the usual tracepoints found in mmu.c. Correct this discrepancy by adding the missing trace points to the TDP MMU. Tested: ran the demand paging selftest on an Intel Skylake machine with all the trace points used by the TDP MMU enabled and observed them firing with expected values. This patch can be viewed in Gerrit at: https://linux-review.googlesource.com/c/virt/kvm/kvm/+/3812Signed-off-by: Ben Gardon <bgardon@google.com> Message-Id: <20201027175944.1183301-1-bgardon@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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- 16 Nov, 2020 5 commits
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Paolo Bonzini authored
Similarly to what vmx/vmx.c does, use vcpu->arch.cr4 to check if CR4 bits PGE, PKE and OSXSAVE have changed. When switching between VMCB01 and VMCB02, CPUID has to be adjusted every time if CR4.PKE or CR4.OSXSAVE change; without this patch, instead, CR4 would be checked against the previous value for L2 on vmentry, and against the previous value for L1 on vmexit, and CPUID would not be updated. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Cathy Avery authored
KVM does not have separate ASIDs for L1 and L2; either the nested hypervisor and nested guests share a single ASID, or on older processor the ASID is used only to implement TLB flushing. Either way, ASIDs are handled at the VM level. In preparation for having different VMCBs passed to VMLOAD/VMRUN/VMSAVE for L1 and L2, store the current ASID to struct vcpu_svm and only move it to the VMCB in svm_vcpu_run. This way, TLB flushes can be applied no matter which VMCB will be active during the next svm_vcpu_run. Signed-off-by: Cathy Avery <cavery@redhat.com> Message-Id: <20201011184818.3609-2-cavery@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Alex Shi authored
This macro is useless, and could cause gcc warning: arch/x86/kernel/kvmclock.c:47:0: warning: macro "HV_CLOCK_SIZE" is not used [-Wunused-macros] Let's remove it. Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Sean Christopherson <sean.j.christopherson@intel.com> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Wanpeng Li <wanpengli@tencent.com> Cc: Jim Mattson <jmattson@google.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: x86@kernel.org Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Message-Id: <1604651963-10067-1-git-send-email-alex.shi@linux.alibaba.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Andrew Jones authored
Almost all tests do this anyway and the ones that don't don't appear to care. Only vmx_set_nested_state_test assumes that a feature (VMX) is disabled until later setting the supported CPUIDs. It's better to disable that explicitly anyway. Signed-off-by: Andrew Jones <drjones@redhat.com> Message-Id: <20201111122636.73346-11-drjones@redhat.com> [Restore CPUID_VMX, or vmx_set_nested_state breaks. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Andrew Jones authored
Signed-off-by: Andrew Jones <drjones@redhat.com> Message-Id: <20201111122636.73346-12-drjones@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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- 15 Nov, 2020 14 commits
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Andrew Jones authored
Signed-off-by: Andrew Jones <drjones@redhat.com> Message-Id: <20201111122636.73346-10-drjones@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Andrew Jones authored
Introduce new vm_create variants that also takes a number of vcpus, an amount of per-vcpu pages, and optionally a list of vcpuids. These variants will create default VMs with enough additional pages to cover the vcpu stacks, per-vcpu pages, and pagetable pages for all. The new 'default' variant uses VM_MODE_DEFAULT, whereas the other new variant accepts the mode as a parameter. Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Ben Gardon <bgardon@google.com> Signed-off-by: Andrew Jones <drjones@redhat.com> Message-Id: <20201111122636.73346-6-drjones@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Andrew Jones authored
The code is almost 100% the same anyway. Just move it to common and add a few arch-specific macros. Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Ben Gardon <bgardon@google.com> Signed-off-by: Andrew Jones <drjones@redhat.com> Message-Id: <20201111122636.73346-5-drjones@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Paolo Bonzini authored
Nothing sets USE_CLEAR_DIRTY_LOG anymore, so anything it surrounds is dead code. However, it is the recommended way to use the dirty page bitmap for new enough kernel, so use it whenever KVM has the KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 capability. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Jim Mattson authored
On emulated VM-entry and VM-exit, update the CPUID bits that reflect CR4.OSXSAVE and CR4.PKE. This fixes a bug where the CPUID bits could continue to reflect L2 CR4 values after emulated VM-exit to L1. It also fixes a related bug where the CPUID bits could continue to reflect L1 CR4 values after emulated VM-entry to L2. The latter bug is mainly relevant to SVM, wherein CPUID is not a required intercept. However, it could also be relevant to VMX, because the code to conditionally update these CPUID bits assumes that the guest CPUID and the guest CR4 are always in sync. Fixes: 8eb3f87d ("KVM: nVMX: fix guest CR4 loading when emulating L2 to L1 exit") Fixes: 2acf923e ("KVM: VMX: Enable XSAVE/XRSTOR for guest") Fixes: b9baba86 ("KVM, pkeys: expose CPUID/CR4 to guest") Reported-by: Abhiroop Dabral <adabral@paloaltonetworks.com> Signed-off-by: Jim Mattson <jmattson@google.com> Reviewed-by: Ricardo Koller <ricarkol@google.com> Reviewed-by: Peter Shier <pshier@google.com> Cc: Haozhong Zhang <haozhong.zhang@intel.com> Cc: Dexuan Cui <dexuan.cui@intel.com> Cc: Huaitong Han <huaitong.han@intel.com> Message-Id: <20201029170648.483210-1-jmattson@google.com>
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Paolo Bonzini authored
Add tsc_msrs_test, remove clear_dirty_log_test and alphabetize everything. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Peter Xu authored
It's only used to override the existing dirty ring size/count. If with a bigger ring count, we test async of dirty ring. If with a smaller ring count, we test ring full code path. Async is default. It has no use for non-dirty-ring tests. Reviewed-by: Andrew Jones <drjones@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20201001012241.6208-1-peterx@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Peter Xu authored
Previously the dirty ring test was working in synchronous way, because only with a vmexit (with that it was the ring full event) we'll know the hardware dirty bits will be flushed to the dirty ring. With this patch we first introduce a vcpu kick mechanism using SIGUSR1, which guarantees a vmexit and also therefore the flushing of hardware dirty bits. Once this is in place, we can keep the vcpu dirty work asynchronous of the whole collection procedure now. Still, we need to be very careful that when reaching the ring buffer soft limit (KVM_EXIT_DIRTY_RING_FULL) we must collect the dirty bits before continuing the vcpu. Further increase the dirty ring size to current maximum to make sure we torture more on the no-ring-full case, which should be the major scenario when the hypervisors like QEMU would like to use this feature. Reviewed-by: Andrew Jones <drjones@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20201001012239.6159-1-peterx@redhat.com> [Use KVM_SET_SIGNAL_MASK+sigwait instead of a signal handler. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Peter Xu authored
Add the initial dirty ring buffer test. The current test implements the userspace dirty ring collection, by only reaping the dirty ring when the ring is full. So it's still running synchronously like this: vcpu main thread 1. vcpu dirties pages 2. vcpu gets dirty ring full (userspace exit) 3. main thread waits until full (so hardware buffers flushed) 4. main thread collects 5. main thread continues vcpu 6. vcpu continues, goes back to 1 We can't directly collects dirty bits during vcpu execution because otherwise we can't guarantee the hardware dirty bits were flushed when we collect and we're very strict on the dirty bits so otherwise we can fail the future verify procedure. A follow up patch will make this test to support async just like the existing dirty log test, by adding a vcpu kick mechanism. Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20201001012237.6111-1-peterx@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Peter Xu authored
Provide a hook for the checks after vcpu_run() completes. Preparation for the dirty ring test because we'll need to take care of another exit reason. Reviewed-by: Andrew Jones <drjones@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20201001012235.6063-1-peterx@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Peter Xu authored
Because kvm dirty rings and kvm dirty log is used in an exclusive way, Let's avoid creating the dirty_bitmap when kvm dirty ring is enabled. At the meantime, since the dirty_bitmap will be conditionally created now, we can't use it as a sign of "whether this memory slot enabled dirty tracking". Change users like that to check against the kvm memory slot flags. Note that there still can be chances where the kvm memory slot got its dirty_bitmap allocated, _if_ the memory slots are created before enabling of the dirty rings and at the same time with the dirty tracking capability enabled, they'll still with the dirty_bitmap. However it should not hurt much (e.g., the bitmaps will always be freed if they are there), and the real users normally won't trigger this because dirty bit tracking flag should in most cases only be applied to kvm slots only before migration starts, that should be far latter than kvm initializes (VM starts). Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20201001012226.5868-1-peterx@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Peter Xu authored
There's no good reason to use both the dirty bitmap logging and the new dirty ring buffer to track dirty bits. We should be able to even support both of them at the same time, but it could complicate things which could actually help little. Let's simply make it the rule before we enable dirty ring on any arch, that we don't allow these two interfaces to be used together. The big world switch would be KVM_CAP_DIRTY_LOG_RING capability enablement. That's where we'll switch from the default dirty logging way to the dirty ring way. As long as kvm->dirty_ring_size is setup correctly, we'll once and for all switch to the dirty ring buffer mode for the current virtual machine. Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20201001012224.5818-1-peterx@redhat.com> [Change errno from EINVAL to ENXIO. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Peter Xu authored
This patch is heavily based on previous work from Lei Cao <lei.cao@stratus.com> and Paolo Bonzini <pbonzini@redhat.com>. [1] KVM currently uses large bitmaps to track dirty memory. These bitmaps are copied to userspace when userspace queries KVM for its dirty page information. The use of bitmaps is mostly sufficient for live migration, as large parts of memory are be dirtied from one log-dirty pass to another. However, in a checkpointing system, the number of dirty pages is small and in fact it is often bounded---the VM is paused when it has dirtied a pre-defined number of pages. Traversing a large, sparsely populated bitmap to find set bits is time-consuming, as is copying the bitmap to user-space. A similar issue will be there for live migration when the guest memory is huge while the page dirty procedure is trivial. In that case for each dirty sync we need to pull the whole dirty bitmap to userspace and analyse every bit even if it's mostly zeros. The preferred data structure for above scenarios is a dense list of guest frame numbers (GFN). This patch series stores the dirty list in kernel memory that can be memory mapped into userspace to allow speedy harvesting. This patch enables dirty ring for X86 only. However it should be easily extended to other archs as well. [1] https://patchwork.kernel.org/patch/10471409/Signed-off-by: Lei Cao <lei.cao@stratus.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20201001012222.5767-1-peterx@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Peter Xu authored
The context will be needed to implement the kvm dirty ring. Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20201001012044.5151-5-peterx@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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