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From: Dave Hansen <dave.hansen@intel.com>
To: Sathyanarayanan Kuppuswamy 
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	Borislav Petkov <bp@alien8.de>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Andi Kleen <ak@linux.intel.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Juergen Gross <jgross@suse.com>, Deep Shah <sdeep@vmware.com>,
	"VMware, Inc." <pv-drivers@vmware.com>
Subject: Re: [PATCH] x86/paravirt: Fix build PARAVIRT_XXL=y without XEN_PV
Date: Wed, 17 Nov 2021 15:33:20 -0800	[thread overview]
Message-ID: <99c70f8d-3275-8aed-5bb3-8b386dcb5e82@intel.com> (raw)
In-Reply-To: <d826f932-a6a4-de7d-b0ea-f8e1f9bfe012@linux.intel.com>

On 11/17/21 3:04 PM, Sathyanarayanan Kuppuswamy wrote:
> 1. Directly substitute TDVMCALLs in places where we require emulation.
...
> Since option#1 is not a scalable approach,

Why is this not "scalable"?  Just eyeballing the problem, here's my
laptop's kernel:

$ objdump  -d vmlinux | grep 'hlt ' | awk -F: '{print $1}' |  while read
addr; do  addr2line -e vmlinux $addr; done
arch/x86/include/asm/irqflags.h:51
arch/x86/include/asm/irqflags.h:51
arch/x86/include/asm/irqflags.h:57
arch/x86/include/asm/irqflags.h:57
arch/x86/include/asm/irqflags.h:57
arch/x86/include/asm/irqflags.h:57
arch/x86/include/asm/irqflags.h:51
arch/x86/include/asm/irqflags.h:51
arch/x86/include/asm/irqflags.h:51
arch/x86/kernel/fpu/init.c:84
arch/x86/include/asm/irqflags.h:57

There are a grand total of 3 sites from which a hlt originates.  With
only 11 possible instances and 3 sites to patch, I'm not sure anything
here needs to be "scalable".

I'd suspect half these sites aren't even reachable on a TDX system.

  parent reply	other threads:[~2021-11-17 23:33 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-17 18:14 [PATCH] x86/paravirt: Fix build PARAVIRT_XXL=y without XEN_PV Kirill A. Shutemov
2021-11-17 18:35 ` Peter Zijlstra
2021-11-17 18:42   ` Kirill A. Shutemov
2021-11-17 18:46     ` Sathyanarayanan Kuppuswamy
2021-11-17 18:48       ` Borislav Petkov
2021-11-17 19:11         ` Dave Hansen
2021-11-17 19:13         ` Sathyanarayanan Kuppuswamy
2021-11-17 19:57           ` Dave Hansen
2021-11-17 20:54             ` Sathyanarayanan Kuppuswamy
2021-11-17 21:09               ` Borislav Petkov
2021-11-17 23:04                 ` Sathyanarayanan Kuppuswamy
2021-11-17 23:23                   ` Peter Zijlstra
2021-11-17 23:57                     ` Sathyanarayanan Kuppuswamy
2021-11-17 23:33                   ` Dave Hansen [this message]
2021-11-18  1:26                     ` Sathyanarayanan Kuppuswamy
2021-11-18  9:13                       ` Borislav Petkov
2021-11-17 19:02       ` Peter Zijlstra
2021-11-18  6:23 ` Juergen Gross
2021-11-19 10:21   ` Kirill A. Shutemov
2021-11-19  7:51 ` Lai Jiangshan
2021-11-19 10:20   ` Kirill A. Shutemov
2021-11-19 10:27     ` Juergen Gross
2021-11-20  1:23     ` Lai Jiangshan
2021-11-22 12:55       ` Juergen Gross

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