linux-kernel - Re: [PATCH] KVM: x86: Load DR6 with guest value only before entering .vcpu

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Message-ID: <Z6_dZTbQbgr2iY6Q@google.com>
Date: Fri, 14 Feb 2025 16:18:45 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	John Stultz <jstultz@...gle.com>, Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH] KVM: x86: Load DR6 with guest value only before entering
 .vcpu_run() loop

On Sat, Feb 15, 2025, Paolo Bonzini wrote:
> On 2/15/25 01:06, Sean Christopherson wrote:
> > On Fri, Feb 14, 2025, Paolo Bonzini wrote:
> > > Queued, thanks.
> > 
> > Drat, I was too slow today.  I applied and pushed this to "kvm-x86 fixes" and
> > linux-next (as of yesterday), along with a few other things, I just haven't sent
> > out the "thanks" yet (got sidetracked).
> > 
> > If you want to grab those, here's a semi-impromptu pull request.  Otherwise I'll
> > just drop this particular commit.
> 
> I had "KVM: nSVM: Enter guest mode before initializing nested NPT MMU" on my
> list, but not the others.
> 
> I'll just pull these, thanks.

Heh, while you're here, here's combined pull request for the selftests changes
that missed 6.14 due to the pmu_counters_test snafumi[1][2]?

I'm a-ok if you want to hold off until 6.15.  I have them sitting in a separate
branch (selftests_6.14), and don't anticipate conflicts, so it's no trouble to
carry them until the next merge window.

[1] https://lore.kernel.org/all/Z6qN3wPXH4cbRzLP@google.com
[2] https://lore.kernel.org/all/20250117010718.2328467-5-seanjc@google.com

---
The following changes since commit 10b2c8a67c4b8ec15f9d07d177f63b563418e948:

  Merge tag 'kvm-x86-fixes-6.13-rcN' of https://github.com/kvm-x86/linux into HEAD (2024-12-22 12:59:33 -0500)

are available in the Git repository at:

  https://github.com/kvm-x86/linux.git tags/kvm-x86-selftests-6.14-2

for you to fetch changes up to 54108e73344480c3e5f3799129970009f52c59f4:

  KVM: selftests: Print out the actual Top-Down Slots count on failure (2025-02-12 08:34:56 -0800)

----------------------------------------------------------------
KVM selftests changes for 6.14:

 - Misc cleanups and prep work.

 - Annotate _no_printf() with "printf" so that pr_debug() statements are
   checked by the compiler for default builds (and pr_info() when QUIET).

 - Attempt to whack the last LLC references/misses mole in the Intel PMU
   counters test by adding a data load and doing CLFLUSH{OPT} on the data
   instead of the code being executed.  The theory is that modern Intel CPUs
   have learned new code prefetching tricks that bypass the PMU counters.

 - Fix a flaw in the Intel PMU counters test where it asserts that an event is
   counting correctly without actually knowing what the event counts on the
   underlying hardware.

----------------------------------------------------------------
Chen Ni (1):
      KVM: selftests: Remove unneeded semicolon

Colton Lewis (2):
      KVM: selftests: Fix typos in x86's PMU counter test's macro variable use
      KVM: selftests: Add defines for AMD PMU CPUID features and properties

Isaku Yamahata (1):
      KVM: selftests: Add printf attribute to _no_printf()

Sean Christopherson (7):
      KVM: selftests: Use data load to trigger LLC references/misses in Intel PMU
      KVM: selftests: Add helpers for locally (un)blocking IRQs on x86
      KVM: selftests: Make Intel arch events globally available in PMU counters test
      KVM: selftests: Only validate counts for hardware-supported arch events
      KVM: selftests: Remove dead code in Intel PMU counters test
      KVM: selftests: Drop the "feature event" param from guest test helpers
      KVM: selftests: Print out the actual Top-Down Slots count on failure

 tools/testing/selftests/kvm/access_tracking_perf_test.c |   2 +-
 tools/testing/selftests/kvm/include/test_util.h         |   2 +-
 tools/testing/selftests/kvm/include/x86/processor.h     |  47 +++++++++++++++++++++++++++++++++
 tools/testing/selftests/kvm/x86/hyperv_ipi.c            |   6 +++--
 tools/testing/selftests/kvm/x86/pmu_counters_test.c     | 158 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----------------------------------------------
 tools/testing/selftests/kvm/x86/svm_int_ctl_test.c      |   5 +---
 tools/testing/selftests/kvm/x86/ucna_injection_test.c   |   2 +-
 tools/testing/selftests/kvm/x86/xapic_ipi_test.c        |   3 ++-
 tools/testing/selftests/kvm/x86/xapic_state_test.c      |   4 +--
 tools/testing/selftests/kvm/x86/xen_shinfo_test.c       |   5 +---
 10 files changed, 151 insertions(+), 83 deletions(-)