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: 18415f33e2ac ("cpu/hotplug: Allow "parallel" bringup up to CPUHP_BP_KICK_AP_STATE")
Signed-off-by: Saurabh Sengar <[email protected]>
---
arch/x86/hyperv/hv_vtl.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c
index 96e6c51515f5..b0ab724def17 100644
--- a/arch/x86/hyperv/hv_vtl.c
+++ b/arch/x86/hyperv/hv_vtl.c
@@ -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 +72,8 @@ 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 +200,15 @@ 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 +222,7 @@ 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)
--
2.34.1
From: Saurabh Sengar <[email protected]> Sent: Thursday, February 1, 2024 11:13 PM
>
> 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: 18415f33e2ac ("cpu/hotplug: Allow "parallel" bringup up to CPUHP_BP_KICK_AP_STATE")
> Signed-off-by: Saurabh Sengar <[email protected]>
> ---
> arch/x86/hyperv/hv_vtl.c | 18 ++++++++++++++----
> 1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c
> index 96e6c51515f5..b0ab724def17 100644
> --- a/arch/x86/hyperv/hv_vtl.c
> +++ b/arch/x86/hyperv/hv_vtl.c
> @@ -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 +72,8 @@ 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 +200,15 @@ 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 +222,7 @@ 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)
> --
> 2.34.1
>
Reviewed-by: Michael Kelley <[email protected]>
On Mon, Feb 05, 2024 at 04:36:42PM +0000, Michael Kelley wrote:
> From: Saurabh Sengar <[email protected]> Sent: Thursday, February 1, 2024 11:13 PM
> >
> > 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: 18415f33e2ac ("cpu/hotplug: Allow "parallel" bringup up to CPUHP_BP_KICK_AP_STATE")
> > Signed-off-by: Saurabh Sengar <[email protected]>
> > ---
[...]
>
> Reviewed-by: Michael Kelley <[email protected]>
Applied. Thanks.