[patch] x86/smpboot: Disable parallel bootup if cc_vendor != NONE

From: Thomas Gleixner <tglx@linutronix.de>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: LKML <linux-kernel@vger.kernel.org>,
	x86@kernel.org, David Woodhouse <dwmw2@infradead.org>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Brian Gerst <brgerst@gmail.com>,
	Arjan van de Veen <arjan@linux.intel.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Paul McKenney <paulmck@kernel.org>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Sean Christopherson <seanjc@google.com>,
	Oleksandr Natalenko <oleksandr@natalenko.name>,
	Paul Menzel <pmenzel@molgen.mpg.de>,
	"Guilherme G. Piccoli" <gpiccoli@igalia.com>,
	Piotr Gorski <lucjan.lucjanov@gmail.com>,
	Usama Arif <usama.arif@bytedance.com>,
	Juergen Gross <jgross@suse.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	xen-devel@lists.xenproject.org,
	Russell King <linux@armlinux.org.uk>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-arm-kernel@lists.infradead.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Guo Ren <guoren@kernel.org>,
	linux-csky@vger.kernel.org,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	linux-mips@vger.kernel.org,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Helge Deller <deller@gmx.de>,
	linux-parisc@vger.kernel.org,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	linux-riscv@lists.infradead.org,
	Mark Rutland <mark.rutland@arm.com>,
	Sabin Rapan <sabrapan@amazon.com>,
	"Michael Kelley (LINUX)" <mikelley@microsoft.com>,
	Dave Hansen <dave.hansen@linux.intel.com>
Subject: [patch] x86/smpboot: Disable parallel bootup if cc_vendor != NONE
Date: Tue, 30 May 2023 14:09:17 +0200	[thread overview]
Message-ID: <87cz2ija1e.ffs@tglx> (raw)
In-Reply-To: <87jzwqjeey.ffs@tglx>

The decision to allow parallel bringup of secondary CPUs checks
CC_ATTR_GUEST_STATE_ENCRYPT to detect encrypted guests. Those cannot use
parallel bootup because accessing the local APIC is intercepted and raises
a #VC or #VE, which cannot be handled at that point.

The check works correctly, but only for AMD encrypted guests. TDX does not
set that flag.

Check for cc_vendor != CC_VENDOR_NONE instead. That might be overbroad, but
definitely works for both AMD and Intel.

Fixes: 0c7ffa32dbd6 ("x86/smpboot/64: Implement arch_cpuhp_init_parallel_bringup() and enable it")
Reported-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/smpboot.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1282,7 +1282,7 @@ bool __init arch_cpuhp_init_parallel_bri
 	 * Intel-TDX has a secure RDMSR hypercall, but that needs to be
 	 * implemented seperately in the low level startup ASM code.
 	 */
-	if (cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) {
+	if (cc_get_vendor() != CC_VENDOR_NONE) {
 		pr_info("Parallel CPU startup disabled due to guest state encryption\n");
 		return false;
 	}

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
