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From: Borislav Petkov <bp@alien8.de>
To: Brijesh Singh <brijesh.singh@amd.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
	kvm@vger.kernel.org, ak@linux.intel.com,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Joerg Roedel <jroedel@suse.de>,
	"H. Peter Anvin" <hpa@zytor.com>, Tony Luck <tony.luck@intel.com>,
	Dave Hansen <dave.hansen@intel.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	David Rientjes <rientjes@google.com>,
	Sean Christopherson <seanjc@google.com>
Subject: Re: [RFC Part1 PATCH 06/13] x86/compressed: rescinds and validate the memory used for the GHCB
Date: Wed, 7 Apr 2021 13:16:04 +0200	[thread overview]
Message-ID: <20210407111604.GA25319@zn.tnic> (raw)
In-Reply-To: <c9f60432-2484-be1e-7b08-86dae5aa263f@amd.com>

On Tue, Apr 06, 2021 at 10:47:18AM -0500, Brijesh Singh wrote:
> Before the GHCB is established the caller does not need to save and
> restore MSRs. The page_state_change() uses the GHCB MSR protocol and it
> can be called before and after the GHCB is established hence I am saving
> and restoring GHCB MSRs.

I think you need to elaborate on that, maybe with an example. What the
other sites using the GHCB MSR currently do is:

1. request by writing it
2. read the response

None of them save and restore it.

So why here?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  parent reply	other threads:[~2021-04-07 11:16 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-24 16:44 [RFC Part1 PATCH 00/13] Add AMD Secure Nested Paging (SEV-SNP) Guest Support Brijesh Singh
2021-03-24 16:44 ` [RFC Part1 PATCH 01/13] x86/cpufeatures: Add SEV-SNP CPU feature Brijesh Singh
2021-03-25 10:54   ` Borislav Petkov
2021-03-25 14:50     ` Brijesh Singh
2021-03-25 16:29       ` Borislav Petkov
2021-03-24 16:44 ` [RFC Part1 PATCH 02/13] x86/mm: add sev_snp_active() helper Brijesh Singh
2021-03-24 16:44 ` [RFC Part1 PATCH 03/13] x86: add a helper routine for the PVALIDATE instruction Brijesh Singh
2021-03-26 14:30   ` Borislav Petkov
2021-03-26 15:42     ` Brijesh Singh
2021-03-26 18:22       ` Brijesh Singh
2021-03-26 19:12         ` Borislav Petkov
2021-03-26 20:04           ` Brijesh Singh
2021-03-26 19:22       ` Borislav Petkov
2021-03-26 20:01         ` Brijesh Singh
2021-03-24 16:44 ` [RFC Part1 PATCH 04/13] x86/sev-snp: define page state change VMGEXIT structure Brijesh Singh
2021-04-01 10:32   ` Borislav Petkov
2021-04-01 14:11     ` Brijesh Singh
2021-04-02 15:44       ` Borislav Petkov
2021-03-24 16:44 ` [RFC Part1 PATCH 05/13] X86/sev-es: move few helper functions in common file Brijesh Singh
2021-04-02 19:27   ` Borislav Petkov
2021-04-02 21:33     ` Brijesh Singh
2021-03-24 16:44 ` [RFC Part1 PATCH 06/13] x86/compressed: rescinds and validate the memory used for the GHCB Brijesh Singh
2021-04-06 10:33   ` Borislav Petkov
2021-04-06 15:47     ` Brijesh Singh
2021-04-06 19:42       ` Tom Lendacky
2021-04-07 11:25         ` Borislav Petkov
2021-04-07 19:45           ` Borislav Petkov
2021-04-08 13:57             ` Tom Lendacky
2021-04-07 11:16       ` Borislav Petkov [this message]
2021-04-07 13:35         ` Brijesh Singh
2021-04-07 14:21           ` Tom Lendacky
2021-04-07 17:15             ` Brijesh Singh
2021-03-24 16:44 ` [RFC Part1 PATCH 07/13] x86/compressed: register GHCB memory when SNP is active Brijesh Singh
2021-04-07 11:59   ` Borislav Petkov
2021-04-07 17:34     ` Brijesh Singh
2021-04-07 17:54       ` Tom Lendacky
2021-04-08  8:17       ` Borislav Petkov
2021-03-24 16:44 ` [RFC Part1 PATCH 08/13] x86/sev-es: register GHCB memory when SEV-SNP " Brijesh Singh
2021-04-08  8:38   ` Borislav Petkov
2021-03-24 16:44 ` [RFC Part1 PATCH 09/13] x86/kernel: add support to validate memory in early enc attribute change Brijesh Singh
2021-04-08 11:40   ` Borislav Petkov
2021-04-08 12:25     ` Brijesh Singh
2021-03-24 16:44 ` [RFC Part1 PATCH 10/13] X86: kernel: make the bss.decrypted section shared in RMP table Brijesh Singh
2021-03-24 16:44 ` [RFC Part1 PATCH 11/13] x86/kernel: validate rom memory before accessing when SEV-SNP is active Brijesh Singh
2021-04-09 16:53   ` Borislav Petkov
2021-04-09 17:40     ` Brijesh Singh
2021-03-24 16:44 ` [RFC Part1 PATCH 12/13] x86/sev-es: make GHCB get and put helper accessible outside Brijesh Singh
2021-03-24 16:44 ` [RFC Part1 PATCH 13/13] x86/kernel: add support to validate memory when changing C-bit Brijesh Singh
2021-04-12 11:49   ` Borislav Petkov
2021-04-12 12:55     ` Brijesh Singh
2021-04-12 13:05       ` Borislav Petkov
2021-04-12 14:31         ` Brijesh Singh

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