Skip to content

L
linux
Switch branch/tag
  1. 28 Sep, 2020 4 commits
  3. 22 Sep, 2020 5 commits
  5. 20 Sep, 2020 3 commits
  7. 18 Sep, 2020 2 commits
  9. 17 Sep, 2020 3 commits
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Set LPCR[HDICE] before writing HDEC · 35dfb43c
      Paul Mackerras authored 
      POWER8 and POWER9 machines have a hardware deviation where generation
of a hypervisor decrementer exception is suppressed if the HDICE bit
in the LPCR register is 0 at the time when the HDEC register
decrements from 0 to -1.  When entering a guest, KVM first writes the
HDEC register with the time until it wants the CPU to exit the guest,
and then writes the LPCR with the guest value, which includes
HDICE = 1.  If HDEC decrements from 0 to -1 during the interval
between those two events, it is possible that we can enter the guest
with HDEC already negative but no HDEC exception pending, meaning that
no HDEC interrupt will occur while the CPU is in the guest, or at
least not until HDEC wraps around.  Thus it is possible for the CPU to
keep executing in the guest for a long time; up to about 4 seconds on
POWER8, or about 4.46 years on POWER9 (except that the host kernel
hard lockup detector will fire first).

To fix this, we set the LPCR[HDICE] bit before writing HDEC on guest
entry.
Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      35dfb43c
    • Fabiano Rosas's avatar
      KVM: PPC: Book3S HV: Do not allocate HPT for a nested guest · 05e6295d
      Fabiano Rosas authored 
      The current nested KVM code does not support HPT guests. This is
informed/enforced in some ways:

- Hosts < P9 will not be able to enable the nested HV feature;

- The nested hypervisor MMU capabilities will not contain
  KVM_CAP_PPC_MMU_HASH_V3;

- QEMU reflects the MMU capabilities in the
  'ibm,arch-vec-5-platform-support' device-tree property;

- The nested guest, at 'prom_parse_mmu_model' ignores the
  'disable_radix' kernel command line option if HPT is not supported;

- The KVM_PPC_CONFIGURE_V3_MMU ioctl will fail if trying to use HPT.

There is, however, still a way to start a HPT guest by using
max-compat-cpu=power8 at the QEMU machine options. This leads to the
guest being set to use hash after QEMU calls the KVM_PPC_ALLOCATE_HTAB
ioctl.

With the guest set to hash, the nested hypervisor goes through the
entry path that has no knowledge of nesting (kvmppc_run_vcpu) and
crashes when it tries to execute an hypervisor-privileged (mtspr
HDEC) instruction at __kvmppc_vcore_entry:

root@L1:~ $ qemu-system-ppc64 -machine pseries,max-cpu-compat=power8 ...

<snip>
[  538.543303] CPU: 83 PID: 25185 Comm: CPU 0/KVM Not tainted 5.9.0-rc4 #1
[  538.543355] NIP:  c00800000753f388 LR: c00800000753f368 CTR: c0000000001e5ec0
[  538.543417] REGS: c0000013e91e33b0 TRAP: 0700   Not tainted  (5.9.0-rc4)
[  538.543470] MSR:  8000000002843033 <SF,VEC,VSX,FP,ME,IR,DR,RI,LE>  CR: 22422882  XER: 20040000
[  538.543546] CFAR: c00800000753f4b0 IRQMASK: 3
               GPR00: c0080000075397a0 c0000013e91e3640 c00800000755e600 0000000080000000
               GPR04: 0000000000000000 c0000013eab19800 c000001394de0000 00000043a054db72
               GPR08: 00000000003b1652 0000000000000000 0000000000000000 c0080000075502e0
               GPR12: c0000000001e5ec0 c0000007ffa74200 c0000013eab19800 0000000000000008
               GPR16: 0000000000000000 c00000139676c6c0 c000000001d23948 c0000013e91e38b8
               GPR20: 0000000000000053 0000000000000000 0000000000000001 0000000000000000
               GPR24: 0000000000000001 0000000000000001 0000000000000000 0000000000000001
               GPR28: 0000000000000001 0000000000000053 c0000013eab19800 0000000000000001
[  538.544067] NIP [c00800000753f388] __kvmppc_vcore_entry+0x90/0x104 [kvm_hv]
[  538.544121] LR [c00800000753f368] __kvmppc_vcore_entry+0x70/0x104 [kvm_hv]
[  538.544173] Call Trace:
[  538.544196] [c0000013e91e3640] [c0000013e91e3680] 0xc0000013e91e3680 (unreliable)
[  538.544260] [c0000013e91e3820] [c0080000075397a0] kvmppc_run_core+0xbc8/0x19d0 [kvm_hv]
[  538.544325] [c0000013e91e39e0] [c00800000753d99c] kvmppc_vcpu_run_hv+0x404/0xc00 [kvm_hv]
[  538.544394] [c0000013e91e3ad0] [c0080000072da4fc] kvmppc_vcpu_run+0x34/0x48 [kvm]
[  538.544472] [c0000013e91e3af0] [c0080000072d61b8] kvm_arch_vcpu_ioctl_run+0x310/0x420 [kvm]
[  538.544539] [c0000013e91e3b80] [c0080000072c7450] kvm_vcpu_ioctl+0x298/0x778 [kvm]
[  538.544605] [c0000013e91e3ce0] [c0000000004b8c2c] sys_ioctl+0x1dc/0xc90
[  538.544662] [c0000013e91e3dc0] [c00000000002f9a4] system_call_exception+0xe4/0x1c0
[  538.544726] [c0000013e91e3e20] [c00000000000d140] system_call_common+0xf0/0x27c
[  538.544787] Instruction dump:
[  538.544821] f86d1098 60000000 60000000 48000099 e8ad0fe8 e8c500a0 e9264140 75290002
[  538.544886] 7d1602a6 7cec42a6 40820008 7d0807b4 <7d164ba6> 7d083a14 f90d10a0 480104fd
[  538.544953] ---[ end trace 74423e2b948c2e0c ]---

This patch makes the KVM_PPC_ALLOCATE_HTAB ioctl fail when running in
the nested hypervisor, causing QEMU to abort.
Reported-by: default avatarSatheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Signed-off-by: default avatarFabiano Rosas <farosas@linux.ibm.com>
Reviewed-by: default avatarGreg Kurz <groug@kaod.org>
Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      05e6295d
    • Greg Kurz's avatar
      KVM: PPC: Don't return -ENOTSUPP to userspace in ioctls · 4e1b2ab7
      Greg Kurz authored 
      ENOTSUPP is a linux only thingy, the value of which is unknown to
userspace, not to be confused with ENOTSUP which linux maps to
EOPNOTSUPP, as permitted by POSIX [1]:

[EOPNOTSUPP]
Operation not supported on socket. The type of socket (address family
or protocol) does not support the requested operation. A conforming
implementation may assign the same values for [EOPNOTSUPP] and [ENOTSUP].

Return -EOPNOTSUPP instead of -ENOTSUPP for the following ioctls:
- KVM_GET_FPU for Book3s and BookE
- KVM_SET_FPU for Book3s and BookE
- KVM_GET_DIRTY_LOG for BookE

This doesn't affect QEMU which doesn't call the KVM_GET_FPU and
KVM_SET_FPU ioctls on POWER anyway since they are not supported,
and _buggily_ ignores anything but -EPERM for KVM_GET_DIRTY_LOG.

[1] https://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.htmlSigned-off-by: default avatarGreg Kurz <groug@kaod.org>
Acked-by: default avatarThadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      4e1b2ab7
  11. 14 Sep, 2020 1 commit
  13. 12 Sep, 2020 8 commits
  15. 11 Sep, 2020 9 commits
    • Vitaly Kuznetsov's avatar
      KVM: x86: always allow writing '0' to MSR_KVM_ASYNC_PF_EN · d831de17
      Vitaly Kuznetsov authored 
      Even without in-kernel LAPIC we should allow writing '0' to
MSR_KVM_ASYNC_PF_EN as we're not enabling the mechanism. In
particular, QEMU with 'kernel-irqchip=off' fails to start
a guest with

qemu-system-x86_64: error: failed to set MSR 0x4b564d02 to 0x0

Fixes: 9d3c447c ("KVM: X86: Fix async pf caused null-ptr-deref")
Reported-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200911093147.484565-1-vkuznets@redhat.com>
[Actually commit the version proposed by Sean Christopherson. - Paolo]
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      d831de17
    • David Rientjes's avatar
      KVM: SVM: Periodically schedule when unregistering regions on destroy · 7be74942
      David Rientjes authored 
      There may be many encrypted regions that need to be unregistered when a
SEV VM is destroyed.  This can lead to soft lockups.  For example, on a
host running 4.15:

watchdog: BUG: soft lockup - CPU#206 stuck for 11s! [t_virtual_machi:194348]
CPU: 206 PID: 194348 Comm: t_virtual_machi
RIP: 0010:free_unref_page_list+0x105/0x170
...
Call Trace:
 [<0>] release_pages+0x159/0x3d0
 [<0>] sev_unpin_memory+0x2c/0x50 [kvm_amd]
 [<0>] __unregister_enc_region_locked+0x2f/0x70 [kvm_amd]
 [<0>] svm_vm_destroy+0xa9/0x200 [kvm_amd]
 [<0>] kvm_arch_destroy_vm+0x47/0x200
 [<0>] kvm_put_kvm+0x1a8/0x2f0
 [<0>] kvm_vm_release+0x25/0x30
 [<0>] do_exit+0x335/0xc10
 [<0>] do_group_exit+0x3f/0xa0
 [<0>] get_signal+0x1bc/0x670
 [<0>] do_signal+0x31/0x130

Although the CLFLUSH is no longer issued on every encrypted region to be
unregistered, there are no other changes that can prevent soft lockups for
very large SEV VMs in the latest kernel.

Periodically schedule if necessary.  This still holds kvm->lock across the
resched, but since this only happens when the VM is destroyed this is
assumed to be acceptable.
Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Message-Id: <alpine.DEB.2.23.453.2008251255240.2987727@chino.kir.corp.google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      7be74942
    • Huacai Chen's avatar
      KVM: MIPS: Change the definition of kvm type · 15e9e35c
      Huacai Chen authored 
      MIPS defines two kvm types:

 #define KVM_VM_MIPS_TE          0
 #define KVM_VM_MIPS_VZ          1

In Documentation/virt/kvm/api.rst it is said that "You probably want to
use 0 as machine type", which implies that type 0 be the "automatic" or
"default" type. And, in user-space libvirt use the null-machine (with
type 0) to detect the kvm capability, which returns "KVM not supported"
on a VZ platform.

I try to fix it in QEMU but it is ugly:
https://lists.nongnu.org/archive/html/qemu-devel/2020-08/msg05629.html

And Thomas Huth suggests me to change the definition of kvm type:
https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg03281.html

So I define like this:

 #define KVM_VM_MIPS_AUTO        0
 #define KVM_VM_MIPS_VZ          1
 #define KVM_VM_MIPS_TE          2

Since VZ and TE cannot co-exists, using type 0 on a TE platform will
still return success (so old user-space tools have no problems on new
kernels); the advantage is that using type 0 on a VZ platform will not
return failure. So, the only problem is "new user-space tools use type
2 on old kernels", but if we treat this as a kernel bug, we can backport
this patch to old stable kernels.
Signed-off-by: default avatarHuacai Chen <chenhc@lemote.com>
Message-Id: <1599734031-28746-1-git-send-email-chenhc@lemote.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      15e9e35c
    • Lai Jiangshan's avatar
      kvm x86/mmu: use KVM_REQ_MMU_SYNC to sync when needed · f6f6195b
      Lai Jiangshan authored 
      When kvm_mmu_get_page() gets a page with unsynced children, the spt
pagetable is unsynchronized with the guest pagetable. But the
guest might not issue a "flush" operation on it when the pagetable
entry is changed from zero or other cases. The hypervisor has the
responsibility to synchronize the pagetables.

KVM behaved as above for many years, But commit 8c8560b8
("KVM: x86/mmu: Use KVM_REQ_TLB_FLUSH_CURRENT for MMU specific flushes")
inadvertently included a line of code to change it without giving any
reason in the changelog. It is clear that the commit's intention was to
change KVM_REQ_TLB_FLUSH -> KVM_REQ_TLB_FLUSH_CURRENT, so we don't
needlessly flush other contexts; however, one of the hunks changed
a nearby KVM_REQ_MMU_SYNC instead.  This patch changes it back.

Link: https://lore.kernel.org/lkml/20200320212833.3507-26-sean.j.christopherson@intel.com/
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarLai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20200902135421.31158-1-jiangshanlai@gmail.com>
fixes: 8c8560b8 ("KVM: x86/mmu: Use KVM_REQ_TLB_FLUSH_CURRENT for MMU specific flushes")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      f6f6195b
    • Chenyi Qiang's avatar
      KVM: nVMX: Fix the update value of nested load IA32_PERF_GLOBAL_CTRL control · c6b177a3
      Chenyi Qiang authored 
      A minor fix for the update of VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL field
in exit_ctls_high.

Fixes: 03a8871a ("KVM: nVMX: Expose load IA32_PERF_GLOBAL_CTRL
VM-{Entry,Exit} control")
Signed-off-by: default avatarChenyi Qiang <chenyi.qiang@intel.com>
Reviewed-by: default avatarXiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200828085622.8365-5-chenyi.qiang@intel.com>
Reviewed-by: default avatarJim Mattson <jmattson@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      c6b177a3
    • Rustam Kovhaev's avatar
      KVM: fix memory leak in kvm_io_bus_unregister_dev() · f6588660
      Rustam Kovhaev authored 
      when kmalloc() fails in kvm_io_bus_unregister_dev(), before removing
the bus, we should iterate over all other devices linked to it and call
kvm_iodevice_destructor() for them

Fixes: 90db1043 ("KVM: kvm_io_bus_unregister_dev() should never fail")
Cc: stable@vger.kernel.org
Reported-and-tested-by: syzbot+f196caa45793d6374707@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=f196caa45793d6374707Signed-off-by: default avatarRustam Kovhaev <rkovhaev@gmail.com>
Reviewed-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200907185535.233114-1-rkovhaev@gmail.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      f6588660
    • Haiwei Li's avatar
      KVM: Check the allocation of pv cpu mask · 0f990222
      Haiwei Li authored 
      check the allocation of per-cpu __pv_cpu_mask. Initialize ops only when
successful.
Signed-off-by: default avatarHaiwei Li <lihaiwei@tencent.com>
Message-Id: <d59f05df-e6d3-3d31-a036-cc25a2b2f33f@gmail.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      0f990222
    • Peter Shier's avatar
      KVM: nVMX: Update VMCS02 when L2 PAE PDPTE updates detected · 43fea4e4
      Peter Shier authored 
      When L2 uses PAE, L0 intercepts of L2 writes to CR0/CR3/CR4 call
load_pdptrs to read the possibly updated PDPTEs from the guest
physical address referenced by CR3.  It loads them into
vcpu->arch.walk_mmu->pdptrs and sets VCPU_EXREG_PDPTR in
vcpu->arch.regs_dirty.

At the subsequent assumed reentry into L2, the mmu will call
vmx_load_mmu_pgd which calls ept_load_pdptrs. ept_load_pdptrs sees
VCPU_EXREG_PDPTR set in vcpu->arch.regs_dirty and loads
VMCS02.GUEST_PDPTRn from vcpu->arch.walk_mmu->pdptrs[]. This all works
if the L2 CRn write intercept always resumes L2.

The resume path calls vmx_check_nested_events which checks for
exceptions, MTF, and expired VMX preemption timers. If
vmx_check_nested_events finds any of these conditions pending it will
reflect the corresponding exit into L1. Live migration at this point
would also cause a missed immediate reentry into L2.

After L1 exits, vmx_vcpu_run calls vmx_register_cache_reset which
clears VCPU_EXREG_PDPTR in vcpu->arch.regs_dirty.  When L2 next
resumes, ept_load_pdptrs finds VCPU_EXREG_PDPTR clear in
vcpu->arch.regs_dirty and does not load VMCS02.GUEST_PDPTRn from
vcpu->arch.walk_mmu->pdptrs[]. prepare_vmcs02 will then load
VMCS02.GUEST_PDPTRn from vmcs12->pdptr0/1/2/3 which contain the stale
values stored at last L2 exit. A repro of this bug showed L2 entering
triple fault immediately due to the bad VMCS02.GUEST_PDPTRn values.

When L2 is in PAE paging mode add a call to ept_load_pdptrs before
leaving L2. This will update VMCS02.GUEST_PDPTRn if they are dirty in
vcpu->arch.walk_mmu->pdptrs[].

Tested:
kvm-unit-tests with new directed test: vmx_mtf_pdpte_test.
Verified that test fails without the fix.

Also ran Google internal VMM with an Ubuntu 16.04 4.4.0-83 guest running a
custom hypervisor with a 32-bit Windows XP L2 guest using PAE. Prior to fix
would repro readily. Ran 14 simultaneous L2s for 140 iterations with no
failures.
Signed-off-by: default avatarPeter Shier <pshier@google.com>
Reviewed-by: default avatarJim Mattson <jmattson@google.com>
Message-Id: <20200820230545.2411347-1-pshier@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      43fea4e4
    • Paolo Bonzini's avatar
      Merge tag 'kvmarm-fixes-5.9-1' of... · 1b67fd08
      Paolo Bonzini authored 
      Merge tag 'kvmarm-fixes-5.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for Linux 5.9, take #1

- Multiple stolen time fixes, with a new capability to match x86
- Fix for hugetlbfs mappings when PUD and PMD are the same level
- Fix for hugetlbfs mappings when PTE mappings are enforced
  (dirty logging, for example)
- Fix tracing output of 64bit values
      1b67fd08
  17. 07 Sep, 2020 5 commits
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7