From: Dave Hansen <dave.hansen@intel.com>
To: "Xin Li (Intel)" <xin@zytor.com>, linux-kernel@vger.kernel.org
Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
andrew.cooper3@citrix.com
Subject: Re: [PATCH v1 1/1] x86/fred: Fix the FRED RSP0 MSR out of sync with its per CPU cache
Date: Wed, 8 Jan 2025 12:14:18 -0800 [thread overview]
Message-ID: <a7bc02bd-035b-4930-a569-3438b47ade19@intel.com> (raw)
In-Reply-To: <20250108023641.17396-1-xin@zytor.com>
On 1/7/25 18:36, Xin Li (Intel) wrote:
> + * Another option is to leave the FRED RSP0 MSR as-is, because the RESET
> + * state of FRED MSRs is zero and INIT does not change the value of the
> + * FRED MSRs in a CPU offline/online cycle. But it doesn't seem safe to
> + * depend on the properties of INIT as that's way too many things that
> + * could cause bugs.
Wouldn't that also open us up to kexec problems? If the last kernel
(maybe not even Linux) left RSP0 set, then the current kernel might
eventually try to run userspace with the old kernel's RSP0 value.
next prev parent reply other threads:[~2025-01-08 20:14 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-08 2:36 [PATCH v1 1/1] x86/fred: Fix the FRED RSP0 MSR out of sync with its per CPU cache Xin Li (Intel)
2025-01-08 3:27 ` H. Peter Anvin
2025-01-08 20:14 ` Dave Hansen [this message]
2025-01-08 21:10 ` Andrew Cooper
2025-01-08 22:31 ` Dave Hansen
2025-01-08 23:32 ` Xin Li
2025-01-09 9:46 ` H. Peter Anvin
2025-01-09 18:48 ` Xin Li
2025-01-08 23:04 ` Dave Hansen
2025-01-08 23:32 ` Xin Li
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