From: Sean Christopherson <seanjc@google.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "Xin Li (Intel)" <xin@zytor.com>,
linux-kernel@vger.kernel.org, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
peterz@infradead.org, andrew.cooper3@citrix.com
Subject: Re: [PATCH v1 3/3] x86/entry: Set FRED RSP0 on return to userspace instead of context switch
Date: Wed, 7 Aug 2024 14:55:05 -0700 [thread overview]
Message-ID: <ZrPtOTHBfZ2e6RfV@google.com> (raw)
In-Reply-To: <87ttfw18jy.ffs@tglx>
On Wed, Aug 07, 2024, Thomas Gleixner wrote:
> Though I wonder if this should not have a per CPU cache for that.
>
> if (cpu_feature_enabled(X86_FEATURE_FRED) {
> unsigned long rsp0 = (unsigned long) task_stack_page(current) + THREAD_SIZE;
>
> if (__this_cpu_read(cpu_fred_rsp0) != rsp0) {
> wrmsrns(MSR_IA32_FRED_RSP0, fred_rsp0);
> this_cpu_write(cpu_fred_rsp0, rsp0);
> }
> }
>
> Hmm?
A per-CPU cache would work for KVM too, KVM would just need to stuff the cache
with the guest's value instead of setting _TIF_LOAD_USER_STATES.
next prev parent reply other threads:[~2024-08-07 21:55 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-07 5:47 [PATCH v1 0/3] x86: Write FRED RSP0 on return to userspace Xin Li (Intel)
2024-08-07 5:47 ` [PATCH v1 1/3] x86/entry: Test ti_work for zero before processing individual bits Xin Li (Intel)
2024-08-07 16:21 ` Brian Gerst
2024-08-07 23:03 ` Xin Li
2024-08-07 18:08 ` Thomas Gleixner
2024-08-07 18:21 ` Thomas Gleixner
2024-08-07 23:01 ` Xin Li
2024-08-07 5:47 ` [PATCH v1 2/3] x86/msr: Switch between WRMSRNS and WRMSR with the alternatives mechanism Xin Li (Intel)
2024-08-07 18:11 ` Thomas Gleixner
2024-08-09 23:07 ` Andrew Cooper
2024-08-10 0:01 ` H. Peter Anvin
2024-08-10 0:25 ` Andrew Cooper
2024-08-16 17:52 ` Xin Li
2024-08-16 18:40 ` Andrew Cooper
2024-08-16 19:18 ` H. Peter Anvin
2024-08-16 21:45 ` Andrew Cooper
2024-08-16 21:26 ` H. Peter Anvin
2024-08-16 22:27 ` Andrew Cooper
2024-08-16 22:34 ` Andrew Cooper
2024-08-16 23:03 ` H. Peter Anvin
2024-08-16 22:59 ` H. Peter Anvin
2024-08-17 23:51 ` H. Peter Anvin
2024-08-17 14:23 ` Borislav Petkov
2024-08-17 14:43 ` Borislav Petkov
2024-08-17 15:44 ` Xin Li
2024-08-17 19:22 ` H. Peter Anvin
2024-08-18 5:59 ` Borislav Petkov
2024-08-17 19:22 ` H. Peter Anvin
2024-08-18 5:49 ` Borislav Petkov
2024-08-18 6:16 ` H. Peter Anvin
2024-08-07 5:47 ` [PATCH v1 3/3] x86/entry: Set FRED RSP0 on return to userspace instead of context switch Xin Li (Intel)
2024-08-07 18:39 ` Thomas Gleixner
2024-08-07 21:55 ` Sean Christopherson [this message]
2024-08-07 23:04 ` Thomas Gleixner
2024-08-09 10:45 ` Nikolay Borisov
2024-08-09 17:37 ` Xin Li
2024-08-09 22:43 ` H. Peter Anvin
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