linux.git/arch/x86/hyperv, branch v5.19

x86/Hyper-V: Add SEV negotiate protocol support in Isolation VM

2022-06-15T18:27:40+00:00

Hyper-V Isolation VM current code uses sev_es_ghcb_hv_call()
to read/write MSR via GHCB page and depends on the sev code.
This may cause regression when sev code changes interface
design.

The latest SEV-ES code requires to negotiate GHCB version before
reading/writing MSR via GHCB page and sev_es_ghcb_hv_call() doesn't
work for Hyper-V Isolation VM. Add Hyper-V ghcb related implementation
to decouple SEV and Hyper-V code. Negotiate GHCB version in the
hyperv_init() and use the version to communicate with Hyper-V
in the ghcb hv call function.

Fixes: 2ea29c5abbc2 ("x86/sev: Save the negotiated GHCB version")
Signed-off-by: Tianyu Lan 
Reviewed-by: Michael Kelley 
Link: https://lore.kernel.org/r/20220614014553.1915929-1-ltykernel@gmail.com
Signed-off-by: Wei Liu

Merge tag 'hyperv-next-signed-20220114' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

2022-01-16T13:53:00+00:00

Pull hyperv updates from Wei Liu:

 - More patches for Hyper-V isolation VM support (Tianyu Lan)

 - Bug fixes and clean-up patches from various people

* tag 'hyperv-next-signed-20220114' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
  scsi: storvsc: Fix storvsc_queuecommand() memory leak
  x86/hyperv: Properly deal with empty cpumasks in hyperv_flush_tlb_multi()
  Drivers: hv: vmbus: Initialize request offers message for Isolation VM
  scsi: storvsc: Fix unsigned comparison to zero
  swiotlb: Add CONFIG_HAS_IOMEM check around swiotlb_mem_remap()
  x86/hyperv: Fix definition of hv_ghcb_pg variable
  Drivers: hv: Fix definition of hypercall input & output arg variables
  net: netvsc: Add Isolation VM support for netvsc driver
  scsi: storvsc: Add Isolation VM support for storvsc driver
  hyper-v: Enable swiotlb bounce buffer for Isolation VM
  x86/hyper-v: Add hyperv Isolation VM check in the cc_platform_has()
  swiotlb: Add swiotlb bounce buffer remap function for HV IVM

x86/hyperv: Properly deal with empty cpumasks in hyperv_flush_tlb_multi()

2022-01-10T11:50:20+00:00

KASAN detected the following issue:

 BUG: KASAN: slab-out-of-bounds in hyperv_flush_tlb_multi+0xf88/0x1060
 Read of size 4 at addr ffff8880011ccbc0 by task kcompactd0/33

 CPU: 1 PID: 33 Comm: kcompactd0 Not tainted 5.14.0-39.el9.x86_64+debug #1
 Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine,
     BIOS Hyper-V UEFI Release v4.0 12/17/2019
 Call Trace:
  dump_stack_lvl+0x57/0x7d
  print_address_description.constprop.0+0x1f/0x140
  ? hyperv_flush_tlb_multi+0xf88/0x1060
  __kasan_report.cold+0x7f/0x11e
  ? hyperv_flush_tlb_multi+0xf88/0x1060
  kasan_report+0x38/0x50
  hyperv_flush_tlb_multi+0xf88/0x1060
  flush_tlb_mm_range+0x1b1/0x200
  ptep_clear_flush+0x10e/0x150
...
 Allocated by task 0:
  kasan_save_stack+0x1b/0x40
  __kasan_kmalloc+0x7c/0x90
  hv_common_init+0xae/0x115
  hyperv_init+0x97/0x501
  apic_intr_mode_init+0xb3/0x1e0
  x86_late_time_init+0x92/0xa2
  start_kernel+0x338/0x3eb
  secondary_startup_64_no_verify+0xc2/0xcb

 The buggy address belongs to the object at ffff8880011cc800
  which belongs to the cache kmalloc-1k of size 1024
 The buggy address is located 960 bytes inside of
  1024-byte region [ffff8880011cc800, ffff8880011ccc00)

'hyperv_flush_tlb_multi+0xf88/0x1060' points to
hv_cpu_number_to_vp_number() and '960 bytes' means we're trying to get
VP_INDEX for CPU#240. 'nr_cpus' here is exactly 240 so we're trying to
access past hv_vp_index's last element. This can (and will) happen
when 'cpus' mask is empty and cpumask_last() will return '>=nr_cpus'.

Commit ad0a6bad4475 ("x86/hyperv: check cpu mask after interrupt has
been disabled") tried to deal with empty cpumask situation but
apparently didn't fully fix the issue.

'cpus' cpumask which is passed to hyperv_flush_tlb_multi() is
'mm_cpumask(mm)' (which is '&mm->cpu_bitmap'). This mask changes every
time the particular mm is scheduled/unscheduled on some CPU (see
switch_mm_irqs_off()), disabling IRQs on the CPU which is performing remote
TLB flush has zero influence on whether the particular process can get
scheduled/unscheduled on _other_ CPUs so e.g. in the case where the mm was
scheduled on one other CPU and got unscheduled during
hyperv_flush_tlb_multi()'s execution will lead to cpumask becoming empty.

It doesn't seem that there's a good way to protect 'mm_cpumask(mm)'
from changing during hyperv_flush_tlb_multi()'s execution. It would be
possible to copy it in the very beginning of the function but this is a
waste. It seems we can deal with changing cpumask just fine.

When 'cpus' cpumask changes during hyperv_flush_tlb_multi()'s
execution, there are two possible issues:
- 'Under-flushing': we will not flush TLB on a CPU which got added to
the mask while hyperv_flush_tlb_multi() was already running. This is
not a problem as this is equal to mm getting scheduled on that CPU
right after TLB flush.
- 'Over-flushing': we may flush TLB on a CPU which is already cleared
from the mask. First, extra TLB flush preserves correctness. Second,
Hyper-V's TLB flush hypercall takes 'mm->pgd' argument so Hyper-V may
avoid the flush if CR3 doesn't match.

Fix the immediate issue with cpumask_last()/hv_cpu_number_to_vp_number()
and remove the pointless cpumask_empty() check from the beginning of the
function as it really doesn't protect anything. Also, avoid the hypercall
altogether when 'flush->processor_mask' ends up being empty.

Fixes: ad0a6bad4475 ("x86/hyperv: check cpu mask after interrupt has been disabled")
Signed-off-by: Vitaly Kuznetsov 
Reviewed-by: Michael Kelley 
Link: https://lore.kernel.org/r/20220106094611.1404218-1-vkuznets@redhat.com
Signed-off-by: Wei Liu

x86/hyperv: Fix definition of hv_ghcb_pg variable

2021-12-28T14:18:47+00:00

The percpu variable hv_ghcb_pg is incorrectly defined.  The __percpu
qualifier should be associated with the union hv_ghcb * (i.e.,
a pointer), not with the target of the pointer. This distinction
makes no difference to gcc and the generated code, but sparse
correctly complains.  Fix the definition in the interest of
general correctness in addition to making sparse happy.

No functional change.

Fixes: 0cc4f6d9f0b9 ("x86/hyperv: Initialize GHCB page in Isolation VM")
Reported-by: kernel test robot 
Signed-off-by: Michael Kelley 
Link: https://lore.kernel.org/r/1640662315-22260-2-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu

net: netvsc: Add Isolation VM support for netvsc driver

2021-12-20T18:01:09+00:00

In Isolation VM, all shared memory with host needs to mark visible
to host via hvcall. vmbus_establish_gpadl() has already done it for
netvsc rx/tx ring buffer. The page buffer used by vmbus_sendpacket_
pagebuffer() stills need to be handled. Use DMA API to map/umap
these memory during sending/receiving packet and Hyper-V swiotlb
bounce buffer dma address will be returned. The swiotlb bounce buffer
has been masked to be visible to host during boot up.

rx/tx ring buffer is allocated via vzalloc() and they need to be
mapped into unencrypted address space(above vTOM) before sharing
with host and accessing. Add hv_map/unmap_memory() to map/umap rx
/tx ring buffer.

Signed-off-by: Tianyu Lan 
Reviewed-by: Haiyang Zhang 
Reviewed-by: Michael Kelley 
Link: https://lore.kernel.org/r/20211213071407.314309-6-ltykernel@gmail.com
Signed-off-by: Wei Liu

hyper-v: Enable swiotlb bounce buffer for Isolation VM

2021-12-20T18:01:09+00:00

hyperv Isolation VM requires bounce buffer support to copy
data from/to encrypted memory and so enable swiotlb force
mode to use swiotlb bounce buffer for DMA transaction.

In Isolation VM with AMD SEV, the bounce buffer needs to be
accessed via extra address space which is above shared_gpa_boundary
(E.G 39 bit address line) reported by Hyper-V CPUID ISOLATION_CONFIG.
The access physical address will be original physical address +
shared_gpa_boundary. The shared_gpa_boundary in the AMD SEV SNP
spec is called virtual top of memory(vTOM). Memory addresses below
vTOM are automatically treated as private while memory above
vTOM is treated as shared.

Swiotlb bounce buffer code calls set_memory_decrypted()
to mark bounce buffer visible to host and map it in extra
address space via memremap. Populate the shared_gpa_boundary
(vTOM) via swiotlb_unencrypted_base variable.

The map function memremap() can't work in the early place
(e.g ms_hyperv_init_platform()) and so call swiotlb_update_mem_
attributes() in the hyperv_init().

Signed-off-by: Tianyu Lan 
Reviewed-by: Michael Kelley 
Link: https://lore.kernel.org/r/20211213071407.314309-4-ltykernel@gmail.com
Signed-off-by: Wei Liu

x86/hyperv: Refactor hv_msi_domain_free_irqs()

2021-12-09T10:52:21+00:00

No point in looking up things over and over. Just look up the associated
irq data and work from there.

No functional change.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Jason Gunthorpe 
Acked-by: Wei Liu 
Link: https://lore.kernel.org/r/20211206210224.429625690@linutronix.de

x86/hyperv: Move required MSRs check to initial platform probing

2021-11-15T12:37:08+00:00

Explicitly check for MSR_HYPERCALL and MSR_VP_INDEX support when probing
for running as a Hyper-V guest instead of waiting until hyperv_init() to
detect the bogus configuration.  Add messages to give the admin a heads
up that they are likely running on a broken virtual machine setup.

At best, silently disabling Hyper-V is confusing and difficult to debug,
e.g. the kernel _says_ it's using all these fancy Hyper-V features, but
always falls back to the native versions.  At worst, the half baked setup
will crash/hang the kernel.

Reviewed-by: Vitaly Kuznetsov 
Signed-off-by: Sean Christopherson 
Link: https://lore.kernel.org/r/20211104182239.1302956-3-seanjc@google.com
Signed-off-by: Wei Liu

x86/hyperv: Fix NULL deref in set_hv_tscchange_cb() if Hyper-V setup fails

2021-11-15T12:37:08+00:00

Check for a valid hv_vp_index array prior to derefencing hv_vp_index when
setting Hyper-V's TSC change callback.  If Hyper-V setup failed in
hyperv_init(), the kernel will still report that it's running under
Hyper-V, but will have silently disabled nearly all functionality.

  BUG: kernel NULL pointer dereference, address: 0000000000000010
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: 0000 [#1] SMP
  CPU: 4 PID: 1 Comm: swapper/0 Not tainted 5.15.0-rc2+ #75
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
  RIP: 0010:set_hv_tscchange_cb+0x15/0xa0
  Code: <8b> 04 82 8b 15 12 17 85 01 48 c1 e0 20 48 0d ee 00 01 00 f6 c6 08
  ...
  Call Trace:
   kvm_arch_init+0x17c/0x280
   kvm_init+0x31/0x330
   vmx_init+0xba/0x13a
   do_one_initcall+0x41/0x1c0
   kernel_init_freeable+0x1f2/0x23b
   kernel_init+0x16/0x120
   ret_from_fork+0x22/0x30

Fixes: 93286261de1b ("x86/hyperv: Reenlightenment notifications support")
Cc: stable@vger.kernel.org
Cc: Vitaly Kuznetsov 
Signed-off-by: Sean Christopherson 
Reviewed-by: Vitaly Kuznetsov 
Link: https://lore.kernel.org/r/20211104182239.1302956-2-seanjc@google.com
Signed-off-by: Wei Liu

x86/hyperv: Protect set_hv_tscchange_cb() against getting preempted

2021-10-28T11:59:13+00:00

The following issue is observed with CONFIG_DEBUG_PREEMPT when KVM loads:

 KVM: vmx: using Hyper-V Enlightened VMCS
 BUG: using smp_processor_id() in preemptible [00000000] code: systemd-udevd/488
 caller is set_hv_tscchange_cb+0x16/0x80
 CPU: 1 PID: 488 Comm: systemd-udevd Not tainted 5.15.0-rc5+ #396
 Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.0 12/17/2019
 Call Trace:
  dump_stack_lvl+0x6a/0x9a
  check_preemption_disabled+0xde/0xe0
  ? kvm_gen_update_masterclock+0xd0/0xd0 [kvm]
  set_hv_tscchange_cb+0x16/0x80
  kvm_arch_init+0x23f/0x290 [kvm]
  kvm_init+0x30/0x310 [kvm]
  vmx_init+0xaf/0x134 [kvm_intel]
  ...

set_hv_tscchange_cb() can get preempted in between acquiring
smp_processor_id() and writing to HV_X64_MSR_REENLIGHTENMENT_CONTROL. This
is not an issue by itself: HV_X64_MSR_REENLIGHTENMENT_CONTROL is a
partition-wide MSR and it doesn't matter which particular CPU will be
used to receive reenlightenment notifications. The only real problem can
(in theory) be observed if the CPU whose id was acquired with
smp_processor_id() goes offline before we manage to write to the MSR,
the logic in hv_cpu_die() won't be able to reassign it correctly.

Reported-by: Michael Kelley 
Signed-off-by: Vitaly Kuznetsov 
Link: https://lore.kernel.org/r/20211012155005.1613352-1-vkuznets@redhat.com
Signed-off-by: Wei Liu