[B][SRU][PATCH 0/1] kvm: Add emulation for movups/movupd

[Po-Hsu Lin]

[Impact]
Our Bionic 4.15 kernel lacks of movups/movupd emulation support.

With the following commit added into the emulator test in
ubuntu_kvm_unit_tests:
  commit 8726f9771911d6749dbd36ab2fc70f0f25e2b1a9
  Author: Jacob Xu <jacobhxu at google.com>
  Date: Wed Apr 21 16:12:57 2021 -0700

      x86: add movups/movupd sse testcases to emulator.c

      Here we add movups/movupd tests corresponding to functionality
      introduced in commit 29916968c486 ("kvm: Add emulation for movups/movupd").

      Signed-off-by: Jacob Xu <jacobhxu at google.com>
      Message-Id: <20210421231258.2583654-1-jacobhxu at google.com>
      Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>

It will cause the emulator test in ubuntu_kvm_unit_tests fail with timeout:
  ...
  PASS: movdqu (read)
  PASS: movdqu (write)
  PASS: movaps (read)
  PASS: movaps (write)
  PASS: movapd (read)
  PASS: movapd (write)
  KVM internal error. Suberror: 1
  emulation failure
  RAX=000000000000000a RBX=ffffffffffffe000 RCX=00000000000003fd RDX=00000000000003f8
  RSI=0000000000419991 RDI=0000000000419991 RBP=000000000051b490 RSP=000000000051b470
  R8 =000000000000000a R9 =00000000000003f8 R10=000000000000000d R11=0000000000000000
  R12=ffffffffffffe000 R13=1111111111111111 R14=ffffffffffffd000 R15=3333333333333333
  RIP=0000000000400a1f RFL=00010006 [-----P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
  ES =0010 0000000000000000 ffffffff 00c09300 DPL=0 DS [-WA]
  CS =0008 0000000000000000 ffffffff 00a09b00 DPL=0 CS64 [-RA]
  SS =0010 0000000000000000 ffffffff 00c09300 DPL=0 DS [-WA]
  DS =0010 0000000000000000 ffffffff 00c09300 DPL=0 DS [-WA]
  FS =0010 0000000000000000 ffffffff 00c09300 DPL=0 DS [-WA]
  GS =0010 000000000051a510 ffffffff 00c09300 DPL=0 DS [-WA]
  LDT=0000 0000000000000000 0000ffff 00008200 DPL=0 LDT
  TR =0080 000000000041207a 0000ffff 00008b00 DPL=0 TSS64-busy
  GDT= 000000000041100a 0000106f
  IDT= 0000000000410000 00000fff
  CR0=80010011 CR2=0000000000000000 CR3=0000000001007000 CR4=00000220
  DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000
  DR6=00000000ffff0ff0 DR7=0000000000000400
  EFER=0000000000000500
  Code=00 c7 45 e8 03 00 00 00 c7 45 ec 04 00 00 00 66 0f 6f 45 e0 <0f> 11 03 48 89 de 48 8d 7d e0 e8 e5 f9 ff ff 0f b6 f8 be a1 8f 41 00 b8 00 00 00 00 e8 07
  qemu-system-x86_64: terminating on signal 15 from pid 15758 (timeout)
  FAIL emulator (timeout; duration=90s)

[Fix]
* 29916968c48691 kvm: Add emulation for movups/movupd

This patch can be cherry-picked into Bionic.

It can fix our test failure plus, as mentioned in the commit message,
emulation failures with openbsd as guest and with Windows 10 with
intel HD graphics pass through.

[Test]
Test kernel can be found here:
https://people.canonical.com/~phlin/kernel/lp-1932966-kvm-emulator/

Run the emulator test from ubuntu_kvm_unit_tests, with this patch
applied it will pass without any issue:
  ...
  PASS: movdqu (read)
  PASS: movdqu (write)
  PASS: movaps (read)
  PASS: movaps (write)
  PASS: movapd (read)
  PASS: movapd (write)
  PASS: movups (read)
  PASS: movups (write)
  PASS: movupd (read)
  PASS: movupd (write)
  PASS: movups unaligned
  PASS: movupd unaligned
  PASS: unaligned movaps exception
  PASS: movups unaligned crosspage
  PASS: movups crosspage exception
  PASS: movq (mmx, read)
  PASS: movq (mmx, write)
  PASS: movb $imm, 0(%rip)
  PASS: shld (cl)
  PASS: shrd (cl)
  PASS: mov null, %ss
  PASS: mov null, %ss (with ss.rpl != cpl)
  PASS: Test ret/iret with a nullified segment
  PASS: ltr
  PASS: cmovnel
  SKIP: skipping register-only tests, use kvm.force_emulation_prefix=1 to enable
  PASS: push16
  PASS: cross-page mmio read
  PASS: cross-page mmio write
  PASS: string_io_mmio
  PASS: jump to non-canonical address
  SKIP: illegal movbe
  SUMMARY: 135 tests, 2 skipped
  PASS emulator (135 tests, 2 skipped)

[Where problems could occur]
I didn't see any other patch that claims to be a fix of this one in
the upstream tree. The problem I think of for the moment is that we
might see other failures when using this in the future.


Stefan Fritsch (1):
  kvm: Add emulation for movups/movupd

 arch/x86/kvm/emulate.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

-- 
2.7.4