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From: Borislav Petkov <bp@alien8.de>
To: Brijesh Singh <brijesh.singh@amd.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, tglx@linutronix.de, jroedel@suse.de,
	thomas.lendacky@amd.com, pbonzini@redhat.com, mingo@redhat.com,
	dave.hansen@intel.com, rientjes@google.com, seanjc@google.com,
	peterz@infradead.org, hpa@zytor.com, tony.luck@intel.com
Subject: Re: [PATCH Part1 RFC v2 16/20] x86/kernel: Validate rom memory before accessing when SEV-SNP is active
Date: Thu, 27 May 2021 13:49:05 +0200	[thread overview]
Message-ID: <YK+HMZIgZWwCYKzq@zn.tnic> (raw)
In-Reply-To: <20210430121616.2295-17-brijesh.singh@amd.com>

On Fri, Apr 30, 2021 at 07:16:12AM -0500, Brijesh Singh wrote:
> +	/*
> +	 * The ROM memory is not part of the E820 system RAM and is not pre-validated
> +	 * by the BIOS. The kernel page table maps the ROM region as encrypted memory,
> +	 * the SEV-SNP requires the encrypted memory must be validated before the
> +	 * access. Validate the ROM before accessing it.
> +	 */
> +	n = ((system_rom_resource.end + 1) - video_rom_resource.start) >> PAGE_SHIFT;
> +	early_snp_set_memory_private((unsigned long)__va(video_rom_resource.start),
> +			video_rom_resource.start, n);

From last review:

I don't like this sprinkling of SNP-special stuff that needs to be done,
around the tree. Instead, pls define a function called

        snp_prep_memory(unsigned long pa, unsigned int num_pages, enum operation);

or so which does all the manipulation needed and the callsites only
simply unconditionally call that function so that all detail is
extracted and optimized away when not config-enabled.

-- 
Regards/Gruss,
    Boris.

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

  reply	other threads:[~2021-05-27 11:49 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-30 12:15 [PATCH Part1 RFC v2 00/20] Add AMD Secure Nested Paging (SEV-SNP) Guest Support Brijesh Singh
2021-04-30 12:15 ` [PATCH Part1 RFC v2 01/20] x86/sev: Define the GHCB MSR protocol for AP reset hold Brijesh Singh
2021-04-30 12:15 ` [PATCH Part1 RFC v2 02/20] x86/sev: Save the negotiated GHCB version Brijesh Singh
2021-05-11  9:23   ` Borislav Petkov
2021-05-11 18:29     ` Brijesh Singh
2021-05-11 18:41       ` Borislav Petkov
2021-05-12 14:03         ` Brijesh Singh
2021-05-12 14:31           ` Borislav Petkov
2021-05-12 15:03             ` Brijesh Singh
2021-04-30 12:15 ` [PATCH Part1 RFC v2 03/20] x86/sev: Add support for hypervisor feature VMGEXIT Brijesh Singh
2021-05-11 10:01   ` Borislav Petkov
2021-05-11 18:53     ` Brijesh Singh
2021-05-17 14:40       ` Borislav Petkov
2021-04-30 12:16 ` [PATCH Part1 RFC v2 04/20] x86/sev: Increase the GHCB protocol version Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 05/20] x86/sev: Define SNP Page State Change VMGEXIT structure Brijesh Singh
2021-05-18 10:41   ` Borislav Petkov
2021-05-18 15:06     ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 06/20] x86/sev: Define SNP guest request NAE events Brijesh Singh
2021-05-18 10:45   ` Borislav Petkov
2021-05-18 13:42     ` Brijesh Singh
2021-05-18 13:54       ` Borislav Petkov
2021-05-18 14:13         ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 07/20] x86/sev: Define error codes for reason set 1 Brijesh Singh
2021-05-18 11:05   ` Borislav Petkov
2021-04-30 12:16 ` [PATCH Part1 RFC v2 08/20] x86/mm: Add sev_snp_active() helper Brijesh Singh
2021-05-18 18:11   ` Borislav Petkov
2021-05-19 17:28     ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 09/20] x86/sev: check SEV-SNP features support Brijesh Singh
2021-05-20 16:02   ` Borislav Petkov
2021-05-20 17:40     ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 10/20] x86/sev: Add a helper for the PVALIDATE instruction Brijesh Singh
2021-04-30 13:05   ` Brijesh Singh
2021-05-20 17:32     ` Borislav Petkov
2021-05-20 17:44       ` Brijesh Singh
2021-05-20 17:51         ` Borislav Petkov
2021-05-20 17:57           ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 11/20] x86/compressed: Add helper for validating pages in the decompression stage Brijesh Singh
2021-05-20 17:52   ` Borislav Petkov
2021-05-20 18:05     ` Brijesh Singh
2021-05-25 10:18       ` Borislav Petkov
2021-04-30 12:16 ` [PATCH Part1 RFC v2 12/20] x86/compressed: Register GHCB memory when SEV-SNP is active Brijesh Singh
2021-05-25 10:41   ` Borislav Petkov
2021-04-30 12:16 ` [PATCH Part1 RFC v2 13/20] x86/sev: " Brijesh Singh
2021-05-25 11:11   ` Borislav Petkov
2021-05-25 14:28     ` Brijesh Singh
2021-05-25 14:35       ` Borislav Petkov
2021-05-25 14:47         ` Brijesh Singh
2021-05-26  9:57           ` Borislav Petkov
2021-05-26 13:23             ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 14/20] x86/sev: Add helper for validating pages in early enc attribute changes Brijesh Singh
2021-05-26 10:39   ` Borislav Petkov
2021-05-26 13:34     ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 15/20] x86/kernel: Make the bss.decrypted section shared in RMP table Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 16/20] x86/kernel: Validate rom memory before accessing when SEV-SNP is active Brijesh Singh
2021-05-27 11:49   ` Borislav Petkov [this message]
2021-05-27 12:12     ` Brijesh Singh
2021-05-27 12:23       ` Borislav Petkov
2021-05-27 12:56         ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 17/20] x86/mm: Add support to validate memory when changing C-bit Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 18/20] x86/boot: Add Confidential Computing address to setup_header Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 19/20] x86/sev: Register SNP guest request platform device Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 20/20] virt: Add SEV-SNP guest driver Brijesh Singh

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