linux-kernel - [PATCH 0/4] Process some MMIO-related errors without KVM exit

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Message-ID: <20240923141810.76331-1-iorlov@amazon.com>
Date: Mon, 23 Sep 2024 14:18:06 +0000
From: Ivan Orlov <iorlov@...zon.com>
To: <hpa@...or.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
	<mingo@...hat.com>, <pbonzini@...hat.com>, <seanjc@...gle.com>,
	<shuah@...nel.org>, <tglx@...utronix.de>
CC: Ivan Orlov <iorlov@...zon.com>, <jalliste@...zon.com>,
	<nh-open-source@...zon.com>, <kvm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>,
	<x86@...nel.org>
Subject: [PATCH 0/4] Process some MMIO-related errors without KVM exit

Currently, KVM may return a variety of internal errors to VMM when
accessing MMIO, and some of them could be gracefully handled on the KVM
level instead. Moreover, some of the MMIO-related errors are handled
differently in VMX in comparison with SVM, which produces certain
inconsistency and should be fixed. This patch series introduces
KVM-level handling for the following situations:

1) Guest is accessing MMIO during event delivery: triple fault instead
of internal error on VMX and infinite loop on SVM

2) Guest fetches an instruction from MMIO: inject #UD and resume guest
execution without internal error

Additionaly, this patch series includes a KVM selftest which covers
different cases of MMIO misuse.

Also, update the set_memory_region_test to expect the triple fault when
starting VM with no RAM.

Ivan Orlov (4):
  KVM: vmx, svm, mmu: Fix MMIO during event delivery handling
  KVM: x86: Inject UD when fetching from MMIO
  selftests: KVM: Change expected exit code in test_zero_memory_regions
  selftests: KVM: Add new test for faulty mmio usage

 arch/x86/include/asm/kvm_host.h               |   6 +
 arch/x86/kvm/emulate.c                        |   3 +
 arch/x86/kvm/kvm_emulate.h                    |   1 +
 arch/x86/kvm/mmu/mmu.c                        |  13 +-
 arch/x86/kvm/svm/svm.c                        |   4 +
 arch/x86/kvm/vmx/vmx.c                        |  21 +-
 arch/x86/kvm/x86.c                            |   7 +-
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../selftests/kvm/set_memory_region_test.c    |   3 +-
 .../selftests/kvm/x86_64/faulty_mmio.c        | 199 ++++++++++++++++++
 10 files changed, 242 insertions(+), 16 deletions(-)
 create mode 100644 tools/testing/selftests/kvm/x86_64/faulty_mmio.c

-- 
2.43.0