From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>
Cc: Peter H Anvin <hpa@zytor.com>,
Dave Hansen <dave.hansen@intel.com>,
Tony Luck <tony.luck@intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Andi Kleen <ak@linux.intel.com>,
Kirill Shutemov <kirill.shutemov@linux.intel.com>,
Sean Christopherson <seanjc@google.com>,
Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v4 3/5] x86/topology: Disable CPU online/offline control for TDX guest
Date: Wed, 4 Aug 2021 12:27:26 -0700 [thread overview]
Message-ID: <20210804192729.2902472-4-sathyanarayanan.kuppuswamy@linux.intel.com> (raw)
In-Reply-To: <20210804192729.2902472-1-sathyanarayanan.kuppuswamy@linux.intel.com>
As per Intel TDX Virtual Firmware Design Guide, sec 4.3.5 and
sec 9.4, all unused CPUs are put in spinning state by
TDVF until OS requests for CPU bring-up via mailbox address passed
by ACPI MADT table. Since by default all unused CPUs are always in
spinning state, there is no point in supporting dynamic CPU
online/offline feature. So current generation of TDVF does not
support CPU hotplug feature. It may be supported in next generation.
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Changes since v3:
* Rebased on top of Tom Lendacky's protected guest change.
Changes since v1:
* Replaced is_tdx_guest() check with prot_guest_has(PR_GUEST_TDX).
arch/x86/kernel/tdx.c | 15 +++++++++++++++
arch/x86/kernel/topology.c | 3 ++-
2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c
index 4080f7546e62..1b6ed482c6b6 100644
--- a/arch/x86/kernel/tdx.c
+++ b/arch/x86/kernel/tdx.c
@@ -5,6 +5,7 @@
#define pr_fmt(fmt) "x86/tdx: " fmt
#include <linux/protected_guest.h>
+#include <linux/cpuhotplug.h>
#include <asm/tdx.h>
#include <asm/vmx.h>
@@ -303,6 +304,17 @@ static int tdg_handle_mmio(struct pt_regs *regs, struct ve_info *ve)
return insn.length;
}
+static int tdg_cpu_offline_prepare(unsigned int cpu)
+{
+ /*
+ * Per Intel TDX Virtual Firmware Design Guide,
+ * sec 4.3.5 and sec 9.4, Hotplug is not supported
+ * in TDX platforms. So don't support CPU
+ * offline feature once it is turned on.
+ */
+ return -EOPNOTSUPP;
+}
+
unsigned long tdg_get_ve_info(struct ve_info *ve)
{
u64 ret;
@@ -443,5 +455,8 @@ void __init tdx_early_init(void)
pv_ops.irq.safe_halt = tdg_safe_halt;
pv_ops.irq.halt = tdg_halt;
+ cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "tdg:cpu_hotplug",
+ NULL, tdg_cpu_offline_prepare);
+
pr_info("Guest initialized\n");
}
diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c
index bd83748e2bde..c637f49d029a 100644
--- a/arch/x86/kernel/topology.c
+++ b/arch/x86/kernel/topology.c
@@ -32,6 +32,7 @@
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/irq.h>
+#include <linux/protected_guest.h>
#include <asm/io_apic.h>
#include <asm/cpu.h>
@@ -130,7 +131,7 @@ int arch_register_cpu(int num)
}
}
}
- if (num || cpu0_hotpluggable)
+ if ((num || cpu0_hotpluggable) && !prot_guest_has(PATTR_GUEST_TDX))
per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
--
2.25.1
next prev parent reply other threads:[~2021-08-04 19:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-04 19:27 [PATCH v4 0/5] Add TDX Guest Support (boot fixes) Kuppuswamy Sathyanarayanan
2021-08-04 19:27 ` [PATCH v4 1/5] x86/boot: Add a trampoline for APs booting in 64-bit mode Kuppuswamy Sathyanarayanan
2021-08-04 19:27 ` [PATCH v4 2/5] x86/boot: Avoid #VE during boot for TDX platforms Kuppuswamy Sathyanarayanan
2021-08-04 19:27 ` Kuppuswamy Sathyanarayanan [this message]
2021-08-04 19:27 ` [PATCH v4 4/5] x86/tdx: Forcefully disable legacy PIC for TDX guests Kuppuswamy Sathyanarayanan
2021-08-04 19:27 ` [PATCH v4 5/5] x86: Skip WBINVD instruction for VM guest Kuppuswamy Sathyanarayanan
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