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Date: Mon, 6 May 2024 11:05:17 -0500
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To: Ravi Bangoria <ravi.bangoria@amd.com>, tglx@linutronix.de,
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References: <20240429060643.211-1-ravi.bangoria@amd.com>
 <20240429060643.211-3-ravi.bangoria@amd.com>
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From: Tom Lendacky <thomas.lendacky@amd.com>
Subject: Re: [PATCH 2/3] x86/bus_lock: Add support for AMD
In-Reply-To: <20240429060643.211-3-ravi.bangoria@amd.com>
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On 4/29/24 01:06, Ravi Bangoria wrote:
> Upcoming AMD uarch will support Bus Lock Detect (called Bus Lock Trap
> in AMD docs). Add support for the same in Linux. Bus Lock Detect is
> enumerated with cpuid CPUID Fn0000_0007_ECX_x0 bit [24 / BUSLOCKTRAP].
> It can be enabled through MSR_IA32_DEBUGCTLMSR. When enabled, hardware
> clears DR6[11] and raises a #DB exception on occurrence of Bus Lock if
> CPL > 0. More detail about the feature can be found in AMD APM[1].
> 
> [1]: AMD64 Architecture Programmer's Manual Pub. 40332, Rev. 4.07 - June
>       2023, Vol 2, 13.1.3.6 Bus Lock Trap
>       https://bugzilla.kernel.org/attachment.cgi?id=304653
> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
> ---
>   arch/x86/kernel/cpu/amd.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
> index 39f316d50ae4..013d16479a24 100644
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -1058,6 +1058,8 @@ static void init_amd(struct cpuinfo_x86 *c)
>   
>   	/* AMD CPUs don't need fencing after x2APIC/TSC_DEADLINE MSR writes. */
>   	clear_cpu_cap(c, X86_FEATURE_APIC_MSRS_FENCE);
> +
> +	bus_lock_init();

Can this call and the one in the intel.c be moved to common.c?

Thanks,
Tom

>   }
>   
>   #ifdef CONFIG_X86_32