linux-stable/arch/x86/xen
Lai Jiangshan 5c8f6a2e31 x86/xen: Add xenpv_restore_regs_and_return_to_usermode()
In the native case, PER_CPU_VAR(cpu_tss_rw + TSS_sp0) is the
trampoline stack. But XEN pv doesn't use trampoline stack, so
PER_CPU_VAR(cpu_tss_rw + TSS_sp0) is also the kernel stack.

In that case, source and destination stacks are identical, which means
that reusing swapgs_restore_regs_and_return_to_usermode() in XEN pv
would cause %rsp to move up to the top of the kernel stack and leave the
IRET frame below %rsp.

This is dangerous as it can be corrupted if #NMI / #MC hit as either of
these events occurring in the middle of the stack pushing would clobber
data on the (original) stack.

And, with  XEN pv, swapgs_restore_regs_and_return_to_usermode() pushing
the IRET frame on to the original address is useless and error-prone
when there is any future attempt to modify the code.

 [ bp: Massage commit message. ]

Fixes: 7f2590a110 ("x86/entry/64: Use a per-CPU trampoline stack for IDT entries")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lkml.kernel.org/r/20211126101209.8613-4-jiangshanlai@gmail.com
2021-12-03 19:21:15 +01:00
..
apic.c x86/apic: Cleanup destination mode 2020-10-28 20:26:25 +01:00
debugfs.c
debugfs.h
efi.c efi: x86/xen: switch to efi_get_secureboot_mode helper 2020-11-17 15:09:32 +01:00
enlighten.c x86/xen: switch initial pvops IRQ functions to dummy ones 2021-11-02 08:03:43 -05:00
enlighten_hvm.c x86/xen: remove xen_have_vcpu_info_placement flag 2021-11-02 07:45:44 -05:00
enlighten_pv.c xen: remove highmem remnants 2021-11-02 08:11:02 -05:00
enlighten_pvh.c xen/x86: adjust data placement 2021-10-05 08:36:19 +02:00
grant-table.c x86/xen: open code alloc_vm_area in arch_gnttab_valloc 2020-10-18 09:27:10 -07:00
irq.c x86/xen: switch initial pvops IRQ functions to dummy ones 2021-11-02 08:03:43 -05:00
Kconfig xen/x86: allow PVH Dom0 without XEN_PV=y 2021-10-05 08:35:56 +02:00
Makefile xen/x86: allow PVH Dom0 without XEN_PV=y 2021-10-05 08:35:56 +02:00
mmu.c
mmu.h
mmu_hvm.c proc/vmcore: convert oldmem_pfn_is_ram callback to more generic vmcore callbacks 2021-11-09 10:02:48 -08:00
mmu_pv.c xen: branch for v5.16-rc1 2021-11-10 11:14:21 -08:00
multicalls.c
multicalls.h
p2m.c memblock: use memblock_free for freeing virtual pointers 2021-11-06 13:30:41 -07:00
pci-swiotlb-xen.c xen/pci-swiotlb: reduce visibility of symbols 2021-09-20 17:01:19 +02:00
platform-pci-unplug.c x86: xen: platform-pci-unplug: use pr_err() and pr_warn() instead of raw printk() 2021-08-30 12:09:54 +02:00
pmu.c
pmu.h
setup.c xen: branch for v5.16-rc1 2021-11-10 11:14:21 -08:00
smp.c x86/xen: remove xen_have_vcpu_info_placement flag 2021-11-02 07:45:44 -05:00
smp.h
smp_hvm.c x86/xen: fix 'nopvspin' build error 2021-01-18 07:22:20 +01:00
smp_pv.c x86/smp: Factor out parts of native_smp_prepare_cpus() 2021-11-11 13:09:32 +01:00
spinlock.c x86/xen: don't unbind uninitialized lock_kicker_irq 2020-11-09 07:43:45 -06:00
suspend.c
suspend_hvm.c xen: Move xen_setup_callback_vector() definition to include/xen/hvm.h 2020-06-11 15:15:19 +02:00
suspend_pv.c locking/seqlock, headers: Untangle the spaghetti monster 2020-08-06 16:13:13 +02:00
time.c x86/paravirt: Switch time pvops functions to use static_call() 2021-03-11 16:17:52 +01:00
trace.c
vga.c
xen-asm.S x86/xen: Add xenpv_restore_regs_and_return_to_usermode() 2021-12-03 19:21:15 +01:00
xen-head.S x86/xen: remove 32-bit awareness from startup_xen 2021-11-02 08:11:02 -05:00
xen-ops.h x86/xen: remove xen_have_vcpu_info_placement flag 2021-11-02 07:45:44 -05:00