linux-kernel - [PATCH v6 8/8] KVM: SVM: Delay legacy platform initialization on SNP

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Message-ID: <20241112232253.3379178-9-dionnaglaze@google.com>
Date: Tue, 12 Nov 2024 23:22:47 +0000
From: Dionna Glaze <dionnaglaze@...gle.com>
To: linux-kernel@...r.kernel.org, x86@...nel.org, 
	Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>
Cc: linux-coco@...ts.linux.dev, Dionna Glaze <dionnaglaze@...gle.com>, 
	Ashish Kalra <ashish.kalra@....com>, Tom Lendacky <thomas.lendacky@....com>, 
	John Allen <john.allen@....com>, Herbert Xu <herbert@...dor.apana.org.au>, 
	"David S. Miller" <davem@...emloft.net>, Michael Roth <michael.roth@....com>, 
	Luis Chamberlain <mcgrof@...nel.org>, Russ Weight <russ.weight@...ux.dev>, 
	Danilo Krummrich <dakr@...hat.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	"Rafael J. Wysocki" <rafael@...nel.org>, Tianfei zhang <tianfei.zhang@...el.com>, 
	Alexey Kardashevskiy <aik@....com>, kvm@...r.kernel.org
Subject: [PATCH v6 8/8] KVM: SVM: Delay legacy platform initialization on SNP

When no SEV or SEV-ES guests are active, then the firmware can be
updated while (SEV-SNP) VM guests are active.

CC: Sean Christopherson <seanjc@...gle.com>
CC: Paolo Bonzini <pbonzini@...hat.com>
CC: Thomas Gleixner <tglx@...utronix.de>
CC: Ingo Molnar <mingo@...hat.com>
CC: Borislav Petkov <bp@...en8.de>
CC: Dave Hansen <dave.hansen@...ux.intel.com>
CC: Ashish Kalra <ashish.kalra@....com>
CC: Tom Lendacky <thomas.lendacky@....com>
CC: John Allen <john.allen@....com>
CC: Herbert Xu <herbert@...dor.apana.org.au>
CC: "David S. Miller" <davem@...emloft.net>
CC: Michael Roth <michael.roth@....com>
CC: Luis Chamberlain <mcgrof@...nel.org>
CC: Russ Weight <russ.weight@...ux.dev>
CC: Danilo Krummrich <dakr@...hat.com>
CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC: "Rafael J. Wysocki" <rafael@...nel.org>
CC: Tianfei zhang <tianfei.zhang@...el.com>
CC: Alexey Kardashevskiy <aik@....com>

Co-developed-by: Ashish Kalra <ashish.kalra@....com>
Signed-off-by: Ashish Kalra <ashish.kalra@....com>
Reviewed-by: Ashish Kalra <ashish.kalra@....com>
Signed-off-by: Dionna Glaze <dionnaglaze@...gle.com>
---
 arch/x86/kvm/svm/sev.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 5e6d1f1c14dfd..507ed87749f55 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -444,7 +444,11 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp,
 	if (ret)
 		goto e_no_asid;
 
-	init_args.probe = false;
+	/*
+	 * Setting probe will skip SEV/SEV-ES platform initialization for an SEV-SNP guest in order
+	 * for SNP firmware hotloading to be available when only SEV-SNP VMs are running.
+	 */
+	init_args.probe = vm_type != KVM_X86_SEV_VM && vm_type != KVM_X86_SEV_ES_VM;
 	ret = sev_platform_init(&init_args);
 	if (ret)
 		goto e_free;
-- 
2.47.0.277.g8800431eea-goog