From: Sean Christopherson <seanjc@google.com>
To: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/6] KVM: nVMX: Always use IBPB to properly virtualize IBRS
Date: Tue, 25 Feb 2025 11:50:29 -0800 [thread overview]
Message-ID: <Z74fBQLeXxuiBC-U@google.com> (raw)
In-Reply-To: <20250219220826.2453186-6-yosry.ahmed@linux.dev>
On Wed, Feb 19, 2025, Yosry Ahmed wrote:
> On synthesized nested VM-exits in VMX, an IBPB is performed if IBRS is
> advertised to the guest to properly provide separate prediction domains
> for L1 and L2. However, this is currently conditional on
> X86_FEATURE_USE_IBPB, which depends on the host spectre_v2_user
> mitigation.
>
> In short, if spectre_v2_user=no, IBRS is not virtualized correctly and
> L1 becomes suspectible to attacks from L2. Fix this by performing the
> IBPB regardless of X86_FEATURE_USE_IBPB.
>
> Fixes: 2e7eab81425a ("KVM: VMX: Execute IBPB on emulated VM-exit when guest has IBRS")
> Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
> ---
Acked-by: Sean Christopherson <seanjc@google.com>
next prev parent reply other threads:[~2025-02-25 19:50 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-19 22:08 [PATCH 0/6] IBPB cleanups and a fixup Yosry Ahmed
2025-02-19 22:08 ` [PATCH 1/6] x86/bugs: Move the X86_FEATURE_USE_IBPB check into callers Yosry Ahmed
2025-02-25 19:47 ` Sean Christopherson
2025-02-25 21:28 ` Yosry Ahmed
2025-02-19 22:08 ` [PATCH 2/6] x86/mm: Remove X86_FEATURE_USE_IBPB checks in cond_mitigation() Yosry Ahmed
2025-02-19 22:08 ` [PATCH 3/6] x86/bugs: Remove the X86_FEATURE_USE_IBPB check in ib_prctl_set() Yosry Ahmed
2025-02-19 22:08 ` [PATCH 4/6] x86/bugs: Use a static branch to guard IBPB on vCPU load Yosry Ahmed
2025-02-25 19:49 ` Sean Christopherson
2025-02-25 21:27 ` Yosry Ahmed
2025-02-25 22:40 ` Sean Christopherson
2025-02-26 2:49 ` Yosry Ahmed
2025-02-27 0:46 ` Sean Christopherson
2025-02-27 0:54 ` Yosry Ahmed
2025-02-19 22:08 ` [PATCH 5/6] KVM: nVMX: Always use IBPB to properly virtualize IBRS Yosry Ahmed
2025-02-19 23:09 ` Jim Mattson
2025-02-25 19:50 ` Sean Christopherson [this message]
2025-02-19 22:08 ` [PATCH 6/6] x86/bugs: Remove X86_FEATURE_USE_IBPB Yosry Ahmed
2025-02-20 19:04 ` [PATCH 0/6] IBPB cleanups and a fixup Josh Poimboeuf
2025-02-20 19:59 ` Yosry Ahmed
2025-02-20 20:47 ` Josh Poimboeuf
2025-02-20 21:50 ` Yosry Ahmed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Z74fBQLeXxuiBC-U@google.com \
--to=seanjc@google.com \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=jpoimboe@kernel.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@redhat.com \
--cc=pawan.kumar.gupta@linux.intel.com \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
--cc=yosry.ahmed@linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.