From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f201.google.com (mail-pg1-f201.google.com [209.85.215.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 534A020C48A for ; Thu, 29 Jan 2026 15:19:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769699943; cv=none; b=kQaovx2BjJVQTDEzucrwbS4OFGJSddSsHABW+gD8s2qshDBpBnIHJ4EBP0Cb9n3ITofUZ7BMrHgxbwMigg178H+ZuZf/LY7ZKQfGCa4aNOulXtND1vrEDsrjtEfdsojmgahAzxgnAa1mAUk0Sp//Ok+hbLzFKGUi4fyN4k9i+u0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769699943; c=relaxed/simple; bh=ySriXi3YnNaDwn3sZpZdzB6TStZI9xdCvV8wCi/xJ/A=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=ad52OkrieqLy80ICzfJrNa7za1h4AIhq78G2i0H5KqnS9a99qO4khMHv0xCYZmFGCDYf3Jnzwdo636T9wi1FRNKtujWzARyOjvXcI7+ahr8MC/G4W7sq9F+OWI680x++jp4DIvOVIKVRDN/H0tBP37bk2sYPi+auQ3nwQF+jNIU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=JFTXwZ+5; arc=none smtp.client-ip=209.85.215.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="JFTXwZ+5" Received: by mail-pg1-f201.google.com with SMTP id 41be03b00d2f7-c337375d953so735013a12.3 for ; Thu, 29 Jan 2026 07:19:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1769699942; x=1770304742; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=vDN7CJht/IWwUBFi7bH7QZjmbW94TeIdtC+sbINM/jw=; b=JFTXwZ+5/f9/Chp9YsjKhzAxGF/dVQxIrdHdQvmrlzlAvxB7ftlSni1B2Oi9hwL/nk EgNj0YIfFfgbo2sGGk6lIvXgEgvvqGwAoQ10D9dGhBwy59WTCCJapAgYWsTvzQe1c58j Uj0bE1yFMpPh943OIlRETBjP9DJDMV1oxE7q3+0n3Jox89E1IrpnB2XieWRQPI+7QhH/ sdyzVjjCofdacQWMLKAmzLL/hV7HB9KwD6Hm8ppsYWuZtHOq9Rq7E3qGFAyVCUqiow+K xkuuNGTOIkENdCeBjLOhle+BE6kcdH6mRAHe979T5DHhHnQTet5WjOvrz6GxzYrC/2b/ ApmA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769699942; x=1770304742; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=vDN7CJht/IWwUBFi7bH7QZjmbW94TeIdtC+sbINM/jw=; b=JPV4KMv3MLDpnTjrS6MaeRV5oPAFV0cTYZ4DhqCtxdMcAwSFW3p+dSxfYUaWD1Q8EK KYnb3/iP1Mcb84iAiUiXwcCJRzn+GvoqfzT6+hfkPG+IfbaEiPn7puJS8Pt/dlPBaE+d CG8kDarTd0g0hqtLVYbzZCcPfnRuFMhqCT/ydjMjgEnU6tl6VsKxalaQtjzuESc93abh ZGLSRiMC4VP6ZvVJ0y2irRy489ks7QRqdcPYVEwAPe7QaJEXT3fJFwdYC2ERbalZyZZX m1x+KnBF3/mcEGM1aVPb2DEtlSM5I4Tq35RrPi/cbf9vY3gAn4POx5uLsNGXmyE4bMqa XiGQ== X-Forwarded-Encrypted: i=1; AJvYcCUMyw0/4je4XFLES+58U2h2Ge196y2Vaeg9sM/5dZQmsF4RmP25e4xwvshwDP3u+U6YVP5cWv0+4bt8ZMs=@vger.kernel.org X-Gm-Message-State: AOJu0Yxz/53XGl8dlfEe3nh8+7fyM02s5wG6K95ek418l+7EEFcJM5xd Nnpjk2J8U3DW4njUibleTPBbRtruX0qpm7LavqbG88M4MKxmTWYMLwY61ATvEQGYJ9TjqU8Qp+7 QWjP4CA== X-Received: from plbli4.prod.google.com ([2002:a17:903:2944:b0:29e:93e9:f1b9]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:320e:b0:2a3:e6fa:4a06 with SMTP id d9443c01a7336-2a870e350c6mr88609495ad.39.1769699941666; Thu, 29 Jan 2026 07:19:01 -0800 (PST) Date: Thu, 29 Jan 2026 07:19:00 -0800 In-Reply-To: <83f9b0a5dd0bc1de9d1e61954f6dd5211df45163.camel@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251229111708.59402-1-khushit.shah@nutanix.com> <83f9b0a5dd0bc1de9d1e61954f6dd5211df45163.camel@infradead.org> Message-ID: Subject: Re: [PATCH v5 4/3] KVM: selftests: Add test cases for EOI suppression modes From: Sean Christopherson To: David Woodhouse Cc: Khushit Shah , pbonzini@redhat.com, kai.huang@intel.com, mingo@redhat.com, x86@kernel.org, bp@alien8.de, hpa@zytor.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, dave.hansen@linux.intel.com, tglx@linutronix.de, jon@nutanix.com, shaju.abraham@nutanix.com Content-Type: text/plain; charset="us-ascii" On Wed, Jan 28, 2026, David Woodhouse wrote: > From: David Woodhouse > > Rather than being frightened of doing the right thing for the in-kernel > I/O APIC because "there might be bugs", I'm not worried about bugs per se, I'm worried about breaking existing guests. Even if KVM is 100% perfect, changes in behavior can still break guests, especially for a feature like this where it seems like everyone got it wrong. And as I said before, I'm not opposed to supporting directed EOI in the in-kernel I/O APIC, but (a) I don't want to do it in conjunction with the fixes for stable@, and (b) I'd prefer to not bother unless there's an actual use case for doing so. The in-kernel I/O APIC isn't being deprecated, but AFAIK it's being de-prioritized by pretty much every VMM. I.e. the risk vs. reward isn't there for me.