From: Sean Christopherson <seanjc@google.com>
To: Aaron Lewis <aaronlewis@google.com>
Cc: kvm@vger.kernel.org, pbonzini@redhat.com, jmattson@google.com
Subject: Re: [kvm-unit-tests PATCH v2 2/4] x86: Align L2's stacks
Date: Wed, 12 Jan 2022 19:38:40 +0000 [thread overview]
Message-ID: <Yd8uQLYAhSppgW74@google.com> (raw)
In-Reply-To: <20211214011823.3277011-3-aaronlewis@google.com>
On Tue, Dec 14, 2021, Aaron Lewis wrote:
> Setting the stack to PAGE_SIZE - 1 sets the stack to being 1-byte
> aligned, which fails in usermode with alignment checks enabled (ie: with
> flags cr0.am set and eflags.ac set). This was causing an #AC in
> usermode.c when preparing to call the callback in run_in_user().
> Aligning the stack fixes the issue.
>
> For the purposes of fixing the #AC in usermode.c the stack has to be
> aligned to at least an 8-byte boundary. Setting it to a page aligned
> boundary ensures any stack alignment requirements are met as x86_64
> stacks generally want to be 16-byte aligned.
>
> Signed-off-by: Aaron Lewis <aaronlewis@google.com>
> ---
Reviewed-by: Sean Christopherson <seanjc@google.com>
next prev parent reply other threads:[~2022-01-12 19:39 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-14 1:18 [kvm-unit-tests PATCH v2 0/4] Add additional testing for routing L2 exceptions Aaron Lewis
2021-12-14 1:18 ` [kvm-unit-tests PATCH v2 1/4] x86: Fix a #GP from occurring in usermode library's exception handlers Aaron Lewis
2021-12-14 1:18 ` [kvm-unit-tests PATCH v2 2/4] x86: Align L2's stacks Aaron Lewis
2022-01-12 19:38 ` Sean Christopherson [this message]
2021-12-14 1:18 ` [kvm-unit-tests PATCH v2 3/4] x86: Add a test framework for nested_vmx_reflect_vmexit() testing Aaron Lewis
2022-01-12 20:48 ` Sean Christopherson
2022-01-19 16:57 ` Aaron Lewis
2022-01-20 0:46 ` Sean Christopherson
2021-12-14 1:18 ` [kvm-unit-tests PATCH v2 4/4] x86: Add test coverage " Aaron Lewis
2021-12-14 12:19 ` [kvm-unit-tests PATCH v2 0/4] Add additional testing for routing L2 exceptions Paolo Bonzini
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