From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.skyhub.de (mail.skyhub.de [5.9.137.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C2E2572 for ; Mon, 23 Aug 2021 09:47:05 +0000 (UTC) Received: from zn.tnic (p200300ec2f07d9000a71bbbd2fefb12e.dip0.t-ipconnect.de [IPv6:2003:ec:2f07:d900:a71:bbbd:2fef:b12e]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id C78C11EC0236; Mon, 23 Aug 2021 11:46:59 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1629712019; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=hTGqJSB99PZEZoaa2JK7dAiOoUAbusV7wq0edRHIa4g=; b=Xl+0l4zzO8gkqhdQvxLoxh3KL93gUcH3KDD59hvOgRQE36+mZUnrVYTwCnD+iTjmwHCIiP osVL7c/3rUhL3Adl9pKRURCPUI5Q8LTL2zMZhvpc1mdFy8wydrUlp+nOJZXEKF1/wJX6Gb OG9ruTq3Y/JCAN274stHJ5fgoZNgwzo= Date: Mon, 23 Aug 2021 11:47:34 +0200 From: Borislav Petkov To: Brijesh Singh Cc: x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, Thomas Gleixner , Ingo Molnar , Joerg Roedel , Tom Lendacky , "H. Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Andy Lutomirski , Dave Hansen , Sergio Lopez , Peter Gonda , Peter Zijlstra , Srinivas Pandruvada , David Rientjes , Dov Murik , Tobin Feldman-Fitzthum , Michael Roth , Vlastimil Babka , "Kirill A . Shutemov" , Andi Kleen , tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com Subject: Re: [PATCH Part1 v5 07/38] x86/sev: Add support for hypervisor feature VMGEXIT Message-ID: References: <20210820151933.22401-1-brijesh.singh@amd.com> <20210820151933.22401-8-brijesh.singh@amd.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210820151933.22401-8-brijesh.singh@amd.com> On Fri, Aug 20, 2021 at 10:19:02AM -0500, Brijesh Singh wrote: > Version 2 of GHCB specification introduced advertisement of a features > that are supported by the hypervisor. Add support to query the HV > features on boot. > > Version 2 of GHCB specification adds several new NAEs, most of them are > optional except the hypervisor feature. Now that hypervisor feature NAE > is implemented, so bump the GHCB maximum support protocol version. > > Signed-off-by: Brijesh Singh > --- > arch/x86/include/asm/mem_encrypt.h | 2 ++ > arch/x86/include/asm/sev-common.h | 3 +++ > arch/x86/include/asm/sev.h | 2 +- > arch/x86/include/uapi/asm/svm.h | 2 ++ > arch/x86/kernel/sev-shared.c | 23 +++++++++++++++++++++++ > 5 files changed, 31 insertions(+), 1 deletion(-) I think you can simplify more. The HV features are read twice - once in the decompressor stub and again in kernel proper - but I guess that's not such a big deal. Also, sev_hv_features can be static. Diff ontop: --- diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h index fb857f2e72cb..df14291d65de 100644 --- a/arch/x86/include/asm/mem_encrypt.h +++ b/arch/x86/include/asm/mem_encrypt.h @@ -26,7 +26,6 @@ enum sev_feature_type { extern u64 sme_me_mask; extern u64 sev_status; -extern u64 sev_hv_features; void sme_encrypt_execute(unsigned long encrypted_kernel_vaddr, unsigned long decrypted_kernel_vaddr, @@ -67,7 +66,6 @@ bool sev_feature_enabled(unsigned int feature_type); #else /* !CONFIG_AMD_MEM_ENCRYPT */ #define sme_me_mask 0ULL -#define sev_hv_features 0ULL static inline void __init sme_early_encrypt(resource_size_t paddr, unsigned long size) { } diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index 8bd67087d79e..d657c2c5a1ee 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -24,7 +24,7 @@ static u16 __ro_after_init ghcb_version; /* Bitmap of SEV features supported by the hypervisor */ -u64 __ro_after_init sev_hv_features = 0; +static u64 __ro_after_init sev_hv_features; static bool __init sev_es_check_cpu_features(void) { @@ -51,10 +51,18 @@ static void __noreturn sev_es_terminate(unsigned int set, unsigned int reason) asm volatile("hlt\n" : : : "memory"); } +/* + * The hypervisor features are available from GHCB version 2 onward. + */ static bool get_hv_features(void) { u64 val; + sev_hv_features = 0; + + if (ghcb_version < 2) + return false; + sev_es_wr_ghcb_msr(GHCB_MSR_HV_FT_REQ); VMGEXIT(); @@ -85,8 +93,7 @@ static bool sev_es_negotiate_protocol(void) ghcb_version = min_t(size_t, GHCB_MSR_PROTO_MAX(val), GHCB_PROTOCOL_MAX); - /* The hypervisor features are available from version 2 onward. */ - if (ghcb_version >= 2 && !get_hv_features()) + if (!get_hv_features()) return false; return true; -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette