Commit 2b4b90e0 authored by Saurabh Sengar's avatar Saurabh Sengar Committed by Wei Liu
Browse files

x86/hyperv: Use per cpu initial stack for vtl context 



Currently, the secondary CPUs in Hyper-V VTL context lack support for
parallel startup. Therefore, relying on the single initial_stack fetched
from the current task structure suffices for all vCPUs.

However, common initial_stack risks stack corruption when parallel startup
is enabled. In order to facilitate parallel startup, use the initial_stack
from the per CPU idle thread instead of the current task.

Fixes: 3be1bc2f ("x86/hyperv: VTL support for Hyper-V")
Signed-off-by: default avatarSaurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: default avatarMichael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/1709452896-13342-1-git-send-email-ssengar@linux.microsoft.com


Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
Message-ID: <1709452896-13342-1-git-send-email-ssengar@linux.microsoft.com>
parent 0e3f7d12

arch/x86/hyperv/hv_vtl.c

+15 −4
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <asm/i8259.h>

#include <asm/mshyperv.h>

#include <asm/realmode.h>

#include <../kernel/smpboot.h>



extern struct boot_params boot_params;

static struct real_mode_header hv_vtl_real_mode_header;
@@ -57,7 +58,7 @@ static void hv_vtl_ap_entry(void) 
	((secondary_startup_64_fn)secondary_startup_64)(&boot_params, &boot_params);

}



static int hv_vtl_bringup_vcpu(u32 target_vp_index, u64 eip_ignored)

static int hv_vtl_bringup_vcpu(u32 target_vp_index, int cpu, u64 eip_ignored)

{

	u64 status;

	int ret = 0;
@@ -71,7 +72,9 @@ static int hv_vtl_bringup_vcpu(u32 target_vp_index, u64 eip_ignored) 
	struct ldttss_desc *ldt;

	struct desc_struct *gdt;



	u64 rsp = current->thread.sp;

	struct task_struct *idle = idle_thread_get(cpu);

	u64 rsp = (unsigned long)idle->thread.sp;



	u64 rip = (u64)&hv_vtl_ap_entry;



	native_store_gdt(&gdt_ptr);
@@ -198,7 +201,15 @@ static int hv_vtl_apicid_to_vp_id(u32 apic_id) 


static int hv_vtl_wakeup_secondary_cpu(u32 apicid, unsigned long start_eip)

{

	int vp_id;

	int vp_id, cpu;



	/* Find the logical CPU for the APIC ID */

	for_each_present_cpu(cpu) {

		if (arch_match_cpu_phys_id(cpu, apicid))

			break;

	}

	if (cpu >= nr_cpu_ids)

		return -EINVAL;



	pr_debug("Bringing up CPU with APIC ID %d in VTL2...\n", apicid);

	vp_id = hv_vtl_apicid_to_vp_id(apicid);
@@ -212,7 +223,7 @@ static int hv_vtl_wakeup_secondary_cpu(u32 apicid, unsigned long start_eip) 
		return -EINVAL;

	}



	return hv_vtl_bringup_vcpu(vp_id, start_eip);

	return hv_vtl_bringup_vcpu(vp_id, cpu, start_eip);

}



int __init hv_vtl_early_init(void)

drivers/hv/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ config HYPERV 
config HYPERV_VTL_MODE

	bool "Enable Linux to boot in VTL context"

	depends on X86_64 && HYPERV

	depends on SMP

	default n

	help

	  Virtual Secure Mode (VSM) is a set of hypervisor capabilities and