From: Xin Li <xin@zytor.com>
To: Sohil Mehta <sohil.mehta@intel.com>,
Sean Christopherson <seanjc@google.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
pbonzini@redhat.com, peterz@infradead.org, brgerst@gmail.com,
tony.luck@intel.com, fenghuay@nvidia.com
Subject: Re: [PATCH v2 1/2] x86/traps: Initialize DR6 by writing its architectural reset value
Date: Tue, 17 Jun 2025 17:42:51 -0700 [thread overview]
Message-ID: <c8b0924e-4cbf-473b-99e2-eb212d8e99bf@zytor.com> (raw)
In-Reply-To: <276d66a1-dafe-4ed8-aefd-8f60e34ff575@intel.com>
On 6/17/2025 4:10 PM, Sohil Mehta wrote:
>> Ah, and now I see that DR6_RESERVED is an existing #define in a uAPI header (Xin
>> said there were a few, but I somehow missed them earlier). Maybe just leave that
>> thing alone, but update the comment to state that it's a historical wart? And
>> then put DR6_ACTIVE_LOW and other macros in arch/x86/include/asm/debugreg.h?
>>
> Yeah, that's unfortunate. Updating the comment seems the best we do for now.
It's a mess, and I don't think I can just remove DR6_RESERVED.
But the value 0xFFFF0FF0 no longer makes sense on newer CPUs, so maybe
it won't cause any real problem?
next prev parent reply other threads:[~2025-06-18 0:43 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-17 7:32 [PATCH v2 0/2] x86/traps: Fix DR6/DR7 initialization Xin Li (Intel)
2025-06-17 7:32 ` [PATCH v2 1/2] x86/traps: Initialize DR6 by writing its architectural reset value Xin Li (Intel)
2025-06-17 9:03 ` Peter Zijlstra
2025-06-17 22:49 ` Xin Li
2025-06-17 18:23 ` Sohil Mehta
2025-06-17 20:47 ` Sean Christopherson
2025-06-17 23:10 ` Sohil Mehta
2025-06-18 0:42 ` Xin Li [this message]
2025-06-17 23:57 ` Xin Li
2025-06-18 21:24 ` Sean Christopherson
2025-06-18 21:55 ` Xin Li
2025-06-19 5:16 ` Maciej W. Rozycki
2025-06-17 7:32 ` [PATCH v2 2/2] x86/traps: Initialize DR7 " Xin Li (Intel)
2025-06-17 13:35 ` Sean Christopherson
2025-06-17 23:08 ` Xin Li
2025-06-18 0:15 ` Xin Li
2025-06-18 3:34 ` H. Peter Anvin
2025-06-17 23:10 ` Sohil Mehta
2025-06-18 0:44 ` Xin Li
2025-06-17 9:05 ` [PATCH v2 0/2] x86/traps: Fix DR6/DR7 initialization Peter Zijlstra
2025-06-17 17:55 ` Sohil Mehta
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