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From: Tadeusz Struk <tstruk@gmail.com>
To: Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, llvm@lists.linux.dev,
	linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	syzbot+6cde2282daa792c49ab8@syzkaller.appspotmail.com,
	Tadeusz Struk <tadeusz.struk@linaro.org>
Subject: Re: [PATCH 0/5] x86: uaccess CMPXCHG + KVM bug fixes
Date: Tue, 1 Feb 2022 09:09:49 -0800	[thread overview]
Message-ID: <d065921b-784c-be0c-3ad2-f2ededb201ac@gmail.com> (raw)
In-Reply-To: <20220201010838.1494405-1-seanjc@google.com>

On 1/31/22 17:08, Sean Christopherson wrote:
> Add uaccess macros for doing CMPXCHG on userspace addresses and use the
> macros to fix KVM bugs by replacing flawed code that maps memory into the
> kernel address space without proper mmu_notifier protection (or with
> broken pfn calculations in one case).
> 
> Add yet another Kconfig for guarding asm_volatile_goto() to workaround a
> clang-13 bug.  I've verified the test passes on gcc versions of arm64,
> PPC, RISC-V, and s390x that also pass the CC_HAS_ASM_GOTO_OUTPUT test.
> 
> Patches 1-4 are tagged for stable@ as patches 3 and 4 (mostly 3) need a
> backportable fix, and doing CMPXCHG on the userspace address is the
> simplest fix from a KVM perspective.
> 
> Peter Zijlstra (1):
>    x86/uaccess: Implement macros for CMPXCHG on user addresses
> 
> Sean Christopherson (4):
>    Kconfig: Add option for asm goto w/ tied outputs to workaround
>      clang-13 bug
>    KVM: x86: Use __try_cmpxchg_user() to update guest PTE A/D bits
>    KVM: x86: Use __try_cmpxchg_user() to emulate atomic accesses
>    KVM: x86: Bail to userspace if emulation of atomic user access faults
> 
>   arch/x86/include/asm/uaccess.h | 131 +++++++++++++++++++++++++++++++++
>   arch/x86/kvm/mmu/paging_tmpl.h |  45 +----------
>   arch/x86/kvm/x86.c             |  35 ++++-----
>   init/Kconfig                   |   4 +
>   4 files changed, 150 insertions(+), 65 deletions(-)

This also fixes the following syzbot issue:
https://syzkaller.appspot.com/bug?id=6cb6102a0a7b0c52060753dd62d070a1d1e71347

Tested-by: Tadeusz Struk <tadeusz.struk@linaro.org>

--
Thanks,
Tadeusz

      parent reply	other threads:[~2022-02-01 17:09 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-01  1:08 [PATCH 0/5] x86: uaccess CMPXCHG + KVM bug fixes Sean Christopherson
2022-02-01  1:08 ` [PATCH 1/5] Kconfig: Add option for asm goto w/ tied outputs to workaround clang-13 bug Sean Christopherson
2022-02-01 20:16   ` Nick Desaulniers
2022-02-01 20:56     ` Sean Christopherson
2022-02-01 21:15       ` Nick Desaulniers
2022-02-01  1:08 ` [PATCH 2/5] x86/uaccess: Implement macros for CMPXCHG on user addresses Sean Christopherson
2022-02-01  1:08 ` [PATCH 3/5] KVM: x86: Use __try_cmpxchg_user() to update guest PTE A/D bits Sean Christopherson
2022-02-01  7:01   ` kernel test robot
2022-02-01  7:01     ` kernel test robot
2022-02-01 19:44     ` Sean Christopherson
2022-02-01 19:44       ` Sean Christopherson
2022-02-01 19:53       ` Nick Desaulniers
2022-02-01 19:53         ` Nick Desaulniers
2022-02-01 13:25   ` kernel test robot
2022-02-01 13:25     ` kernel test robot
2022-02-01  1:08 ` [PATCH 4/5] KVM: x86: Use __try_cmpxchg_user() to emulate atomic accesses Sean Christopherson
2022-02-01  9:25   ` kernel test robot
2022-02-01  9:25     ` kernel test robot
2022-02-01  1:08 ` [PATCH 5/5] KVM: x86: Bail to userspace if emulation of atomic user access faults Sean Christopherson
2022-02-01 17:09 ` Tadeusz Struk [this message]

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