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From: Sean Christopherson <seanjc@google.com>
To: Tom Lendacky <thomas.lendacky@amd.com>
Cc: "Kuppuswamy,
	Sathyanarayanan"  <sathyanarayanan.kuppuswamy@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Tony Luck <tony.luck@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Andi Kleen <ak@linux.intel.com>,
	Kirill Shutemov <kirill.shutemov@linux.intel.com>,
	Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 05/10] x86/tdx: Handle port I/O
Date: Fri, 15 Oct 2021 00:45:15 +0000	[thread overview]
Message-ID: <YWjPG7h/fzupVPnA@google.com> (raw)
In-Reply-To: <0f2a09ca-b098-03ba-a166-6f31c718220b@amd.com>

On Thu, Sep 23, 2021, Tom Lendacky wrote:
> On 9/23/21 12:24 PM, Kuppuswamy, Sathyanarayanan wrote:
> > Any reason for using sev_enable_key over CC attribute? IMO, CC attribute
> > exist to generalize the common feature code. My impression is SEV is
> > specific to AMD code.

Unless CC attributes have static_<whatever> support, that would add a CMP+Jcc to
every I/O instruction in the kernel.

> When the SEV series was initially submitted, it originally did an
> sev_active() check. For various reasons a static key and the
> sev_key_active() call was requested.
> 
> My suggestion was to change the name to something that doesn't have SEV/sev
> in it that can be used by both SEV and TDX. The sev_enable_key can be moved
> to a common file (maybe cc_platform.c) and renamed. Then
> arch/x86/include/asm/io.h can change the #ifdef from CONFIG_AMD_MEM_ENCRYPT
> to CONFIG_ARCH_HAS_CC_PLATFORM.
> 
> Not sure if anyone else feels the same, though, so just my suggestion.

+1 to a static key to gate high volume and/or performance critical things that
are common to SEV and TDX.

  reply	other threads:[~2021-10-15  0:45 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-22 22:52 [PATCH v6 00/10] Add TDX Guest Support (#VE handler support) Kuppuswamy Sathyanarayanan
2021-09-22 22:52 ` [PATCH v6 01/10] x86/io: Allow to override inX() and outX() implementation Kuppuswamy Sathyanarayanan
2021-09-22 22:52 ` [PATCH v6 02/10] x86/tdx: Add early_is_tdx_guest() interface Kuppuswamy Sathyanarayanan
2021-09-22 22:52 ` [PATCH v6 03/10] x86/tdx: Handle port I/O in decompression code Kuppuswamy Sathyanarayanan
2021-09-22 22:52 ` [PATCH v6 04/10] x86/tdx: Handle early IO operations Kuppuswamy Sathyanarayanan
2021-09-22 22:52 ` [PATCH v6 05/10] x86/tdx: Handle port I/O Kuppuswamy Sathyanarayanan
2021-09-23 16:32   ` Tom Lendacky
2021-09-23 17:24     ` Kuppuswamy, Sathyanarayanan
2021-09-23 17:59       ` Tom Lendacky
2021-10-15  0:45         ` Sean Christopherson [this message]
2021-09-22 22:52 ` [PATCH v6 06/10] x86/insn-eval: Introduce insn_get_modrm_reg_ptr() Kuppuswamy Sathyanarayanan
2021-09-22 22:52 ` [PATCH v6 07/10] x86/insn-eval: Introduce insn_decode_mmio() Kuppuswamy Sathyanarayanan
2021-09-22 22:52 ` [PATCH v6 08/10] x86/sev-es: Use insn_decode_mmio() for MMIO implementation Kuppuswamy Sathyanarayanan
2021-09-22 22:52 ` [PATCH v6 09/10] x86/tdx: Handle in-kernel MMIO Kuppuswamy Sathyanarayanan
2021-09-22 22:52 ` [PATCH v6 10/10] x86/tdx: Handle MWAIT and MONITOR Kuppuswamy Sathyanarayanan

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