x86/xen: move paravirt lazy code

Only Xen is using the paravirt lazy mode code, so it can be moved to
Xen specific sources.

This allows to make some of the functions static or to merge them into
th

x86/xen: move paravirt lazy code

Only Xen is using the paravirt lazy mode code, so it can be moved to
Xen specific sources.

This allows to make some of the functions static or to merge them into
their only call sites.

While at it do a rename from "paravirt" to "xen" for all moved
specifiers.

No functional change.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20230913113828.18421-3-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>

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x86/paravirt: Convert simple paravirt functions to asm

All functions referenced via __PV_IS_CALLEE_SAVE() need to be assembler
functions, as those functions calls are hidden from the compiler.

In c

x86/paravirt: Convert simple paravirt functions to asm

All functions referenced via __PV_IS_CALLEE_SAVE() need to be assembler
functions, as those functions calls are hidden from the compiler.

In case the kernel is compiled with "-fzero-call-used-regs" the compiler
will clobber caller-saved registers at the end of C functions, which
will result in unexpectedly zeroed registers at the call site of the
related paravirt functions.

Replace the C functions with DEFINE_PARAVIRT_ASM() constructs using
the same instructions as the related paravirt calls in the
PVOP_ALT_[V]CALLEE*() macros. And since they're not C functions visible
to the compiler anymore, latter won't do the callee-clobbered zeroing
invoked by -fzero-call-used-regs and thus won't corrupt registers.

[ bp: Extend commit message. ]

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230317063325.361-1-jgross@suse.com

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x86/paravirt: Merge activate_mm() and dup_mmap() callbacks

The two paravirt callbacks .mmu.activate_mm() and .mmu.dup_mmap() are
sharing the same implementations in all cases: for Xen PV guests they

x86/paravirt: Merge activate_mm() and dup_mmap() callbacks

The two paravirt callbacks .mmu.activate_mm() and .mmu.dup_mmap() are
sharing the same implementations in all cases: for Xen PV guests they
are pinning the PGD of the new mm_struct, and for all other cases they
are a NOP.

In the end, both callbacks are meant to register an address space with
the underlying hypervisor, so there needs to be only a single callback
for that purpose.

So merge them to a common callback .mmu.enter_mmap() (in contrast to the
corresponding already existing .mmu.exit_mmap()).

As the first parameter of the old callbacks isn't used, drop it from the
replacement one.

[ bp: Remove last occurrence of paravirt_activate_mm() in
asm/mmu_context.h ]

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>
Link: https://lore.kernel.org/r/20230207075902.7539-1-jgross@suse.com

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x86/paravirt: Remove clobber bitmask from .parainstructions

The u16 "clobber" value is not used in .parainstructions since commit
27876f3882fd ("x86/paravirt: Remove clobbers from struct paravirt_pa

x86/paravirt: Remove clobber bitmask from .parainstructions

The u16 "clobber" value is not used in .parainstructions since commit
27876f3882fd ("x86/paravirt: Remove clobbers from struct paravirt_patch_site")

Remove the u16 from the section macro, the argument from all macros, and
all now-unused CLBR_* macros.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220903073706.3193746-1-keescook@chromium.org

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x86/paravirt: Fix a !PARAVIRT build warning

Fix

./include/trace/events/xen.h:28:31: warning: ‘enum paravirt_lazy_mode’ \
declared inside parameter list will not be visible outside of this def

x86/paravirt: Fix a !PARAVIRT build warning

Fix

./include/trace/events/xen.h:28:31: warning: ‘enum paravirt_lazy_mode’ \
declared inside parameter list will not be visible outside of this definition or declaration

which turns into a build error:

./include/trace/events/xen.h:28:50: error: parameter 1 (‘mode’) has incomplete type
28 | TP_PROTO(enum paravirt_lazy_mode mode), \

due to enum paravirt_lazy_mode being visible only under CONFIG_PARAVIRT.
Just pull it up where it is unconditionally visible.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/Y1AtAXM8YjtBm2cj@zn.tnic

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x86/paravirt: Make struct paravirt_call_site unconditionally available

For the upcoming call thunk patching it's less ifdeffery when the data
structure is unconditionally available. The code can the

x86/paravirt: Make struct paravirt_call_site unconditionally available

For the upcoming call thunk patching it's less ifdeffery when the data
structure is unconditionally available. The code can then be trivially
fenced off with IS_ENABLED().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111147.367853167@infradead.org

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x86/paravirt: Remove clobber bitmask from .parainstructions

The u16 "clobber" value is not used in .parainstructions since commit
27876f3882fd ("x86/paravirt: Remove clobbers from struct paravirt_pa

x86/paravirt: Remove clobber bitmask from .parainstructions

The u16 "clobber" value is not used in .parainstructions since commit
27876f3882fd ("x86/paravirt: Remove clobbers from struct paravirt_patch_site")

Remove the u16 from the section macro, the argument from all macros, and
all now-unused CLBR_* macros.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220903073706.3193746-1-keescook@chromium.org

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x86/paravirt: add extra clobbers with ZERO_CALL_USED_REGS enabled

The ZERO_CALL_USED_REGS feature may zero out caller-saved registers
before returning.

In spurious_kernel_fault(), the "pte_offset_k

x86/paravirt: add extra clobbers with ZERO_CALL_USED_REGS enabled

The ZERO_CALL_USED_REGS feature may zero out caller-saved registers
before returning.

In spurious_kernel_fault(), the "pte_offset_kernel()" call results in
this assembly code:

.Ltmp151:
#APP
# ALT: oldnstr
.Ltmp152:
.Ltmp153:
.Ltmp154:
.section .discard.retpoline_safe,"",@progbits
.quad .Ltmp154
.text

callq *pv_ops+536(%rip)

.Ltmp155:
.section .parainstructions,"a",@progbits
.p2align 3, 0x0
.quad .Ltmp153
.byte 67
.byte .Ltmp155-.Ltmp153
.short 1
.text
.Ltmp156:
# ALT: padding
.zero (-(((.Ltmp157-.Ltmp158)-(.Ltmp156-.Ltmp152))>0))*((.Ltmp157-.Ltmp158)-(.Ltmp156-.Ltmp152)),144
.Ltmp159:
.section .altinstructions,"a",@progbits
.Ltmp160:
.long .Ltmp152-.Ltmp160
.Ltmp161:
.long .Ltmp158-.Ltmp161
.short 33040
.byte .Ltmp159-.Ltmp152
.byte .Ltmp157-.Ltmp158
.text

.section .altinstr_replacement,"ax",@progbits
# ALT: replacement 1
.Ltmp158:
movq %rdi, %rax
.Ltmp157:
.text
#NO_APP
.Ltmp162:
testb $-128, %dil

The "testb" here is using %dil, but the %rdi register was cleared before
returning from "callq *pv_ops+536(%rip)". Adding the proper constraints
results in the use of a different register:

movq %r11, %rdi

# Similar to above.

testb $-128, %r11b

Link: https://github.com/KSPP/linux/issues/192
Signed-off-by: Bill Wendling <morbo@google.com>
Reported-and-tested-by: Nathan Chancellor <nathan@kernel.org>
Fixes: 035f7f87b729 ("randstruct: Enable Clang support")
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/lkml/fa6df43b-8a1a-8ad1-0236-94d2a0b588fa@suse.com/
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220902213750.1124421-3-morbo@google.com

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x86/paravirt: clean up typos and grammaros

Drive-by clean up of the comment.

[ Impact: cleanup]

Signed-off-by: Bill Wendling <morbo@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Lin

x86/paravirt: clean up typos and grammaros

Drive-by clean up of the comment.

[ Impact: cleanup]

Signed-off-by: Bill Wendling <morbo@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220902213750.1124421-2-morbo@google.com

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x86/paravirt: Ensure proper alignment

The entries in the .parainstructions sections are 8 byte aligned and the
corresponding C struct paravirt_patch_site makes the array offset 16
bytes.

Though the

x86/paravirt: Ensure proper alignment

The entries in the .parainstructions sections are 8 byte aligned and the
corresponding C struct paravirt_patch_site makes the array offset 16
bytes.

Though the pushed entries are only using 12 bytes, __parainstructions_end
is therefore 4 bytes short.

That works by chance because it's only used in a loop:

for (p = start; p < end; p++)

But this falls flat when calculating the number of elements:

n = end - start

That's obviously off by one.

Ensure that the gap is filled and the last entry is occupying 16 bytes.

[ bp: Add the proper struct and section names. ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220915111142.992398801@infradead.org

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x86/entry,xen: Early rewrite of restore_regs_and_return_to_kernel()

By doing an early rewrite of 'jmp native_iret` in
restore_regs_and_return_to_kernel() we can get rid of the last
INTERRUPT_RETURN

x86/entry,xen: Early rewrite of restore_regs_and_return_to_kernel()

By doing an early rewrite of 'jmp native_iret` in
restore_regs_and_return_to_kernel() we can get rid of the last
INTERRUPT_RETURN user and paravirt_iret.

Suggested-by: Andrew Cooper <Andrew.Cooper3@citrix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.815039833@infradead.org

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x86/paravirt: Use %rip-relative addressing in hook calls

While using a plain (constant) address works, its use needlessly invokes
a SIB addressing mode, making every call site one byte larger than
n

x86/paravirt: Use %rip-relative addressing in hook calls

While using a plain (constant) address works, its use needlessly invokes
a SIB addressing mode, making every call site one byte larger than
necessary:

ff 14 25 98 89 42 82 call *0xffffffff82428998

Instead of using an "i" constraint with address-of operator and a 'c'
operand modifier, simply use an ordinary "m" constraint, which the
64-bit compiler will translate to %rip-relative addressing:

ff 15 62 fb d2 00 call *0xd2fb62(%rip) # ffffffff82428998 <pv_ops+0x18>

This way the compiler is also told the truth about operand usage - the
memory location gets actually read, after all.

32-bit code generation is unaffected by the change.

[ bp: Remove "we", add examples. ]

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/b8192e8a-13ef-6ac6-6364-8ba58992cd1d@suse.com

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mm: x86: Invoke hypercall when page encryption status is changed

Invoke a hypercall when a memory region is changed from encrypted ->
decrypted and vice versa. Hypervisor needs to know the page encr

mm: x86: Invoke hypercall when page encryption status is changed

Invoke a hypercall when a memory region is changed from encrypted ->
decrypted and vice versa. Hypervisor needs to know the page encryption
status during the guest migration.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Steve Rutherford <srutherford@google.com>
Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Message-Id: <0a237d5bb08793916c7790a3e653a2cbe7485761.1629726117.git.ashish.kalra@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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x86/xen: switch initial pvops IRQ functions to dummy ones

The initial pvops functions handling irq flags will only ever be called
before interrupts are being enabled.

So switch them to be dummy fun

x86/xen: switch initial pvops IRQ functions to dummy ones

The initial pvops functions handling irq flags will only ever be called
before interrupts are being enabled.

So switch them to be dummy functions:
- xen_save_fl() can always return 0
- xen_irq_disable() is a nop
- xen_irq_enable() can BUG()

Add some generic paravirt functions for that purpose.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20211028072748.29862-3-jgross@suse.com
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

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x86: Fix various typos in comments

Fix ~144 single-word typos in arch/x86/ code comments.

Doing this in a single commit should reduce the churn.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: B

x86: Fix various typos in comments

Fix ~144 single-word typos in arch/x86/ code comments.

Doing this in a single commit should reduce the churn.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-kernel@vger.kernel.org

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x86/paravirt: Have only one paravirt patch function

There is no need any longer to have different paravirt patch functions
for native and Xen. Eliminate native_patch() and rename
paravirt_patch_defa

x86/paravirt: Have only one paravirt patch function

There is no need any longer to have different paravirt patch functions
for native and Xen. Eliminate native_patch() and rename
paravirt_patch_default() to paravirt_patch().

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210311142319.4723-15-jgross@suse.com

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x86/paravirt: Switch functions with custom code to ALTERNATIVE

Instead of using paravirt patching for custom code sequences use
ALTERNATIVE for the functions with custom code replacements.

Instead

x86/paravirt: Switch functions with custom code to ALTERNATIVE

Instead of using paravirt patching for custom code sequences use
ALTERNATIVE for the functions with custom code replacements.

Instead of patching an ud2 instruction for unpopulated vector entries
into the caller site, use a simple function just calling BUG() as a
replacement.

Simplify the register defines for assembler paravirt calling, as there
isn't much usage left.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210311142319.4723-14-jgross@suse.com

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x86/paravirt: Add new PVOP_ALT* macros to support pvops in ALTERNATIVEs

Instead of using paravirt patching for custom code sequences add
support for using ALTERNATIVE handling combined with paravirt

x86/paravirt: Add new PVOP_ALT* macros to support pvops in ALTERNATIVEs

Instead of using paravirt patching for custom code sequences add
support for using ALTERNATIVE handling combined with paravirt call
patching.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210311142319.4723-13-jgross@suse.com

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x86/paravirt: Switch iret pvops to ALTERNATIVE

The iret paravirt op is rather special as it is using a jmp instead
of a call instruction. Switch it to ALTERNATIVE.

Signed-off-by: Juergen Gross <jgr

x86/paravirt: Switch iret pvops to ALTERNATIVE

The iret paravirt op is rather special as it is using a jmp instead
of a call instruction. Switch it to ALTERNATIVE.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210311142319.4723-12-jgross@suse.com

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x86/paravirt: Simplify paravirt macros

The central pvops call macros ____PVOP_CALL() and ____PVOP_VCALL() are
looking very similar now.

The main differences are using PVOP_VCALL_ARGS or PVOP_CALL_A

x86/paravirt: Simplify paravirt macros

The central pvops call macros ____PVOP_CALL() and ____PVOP_VCALL() are
looking very similar now.

The main differences are using PVOP_VCALL_ARGS or PVOP_CALL_ARGS, which
are identical, and the return value handling.

So drop PVOP_VCALL_ARGS and instead of ____PVOP_VCALL() just use
(void)____PVOP_CALL(long, ...).

Note that it isn't easily possible to just redefine ____PVOP_VCALL()
to use ____PVOP_CALL() instead, as this would require further hiding of
commas in macro parameters.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210311142319.4723-11-jgross@suse.com

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x86/paravirt: Remove no longer needed 32-bit pvops cruft

PVOP_VCALL4() is only used for Xen PV, while PVOP_CALL4() isn't used
at all. Keep PVOP_CALL4() for 64 bits due to symmetry reasons.

This all

x86/paravirt: Remove no longer needed 32-bit pvops cruft

PVOP_VCALL4() is only used for Xen PV, while PVOP_CALL4() isn't used
at all. Keep PVOP_CALL4() for 64 bits due to symmetry reasons.

This allows to remove the 32-bit definitions of those macros leading
to a substantial simplification of the paravirt macros, as those were
the only ones needing non-empty "pre" and "post" parameters.

PVOP_CALLEE2() and PVOP_VCALLEE2() are used nowhere, so remove them.

Another no longer needed case is special handling of return types
larger than unsigned long. Replace that with a BUILD_BUG_ON().

DISABLE_INTERRUPTS() is used in 32-bit code only, so it can just be
replaced by cli.

INTERRUPT_RETURN in 32-bit code can be replaced by iret.

ENABLE_INTERRUPTS is used nowhere, so it can be removed.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210311142319.4723-10-jgross@suse.com

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x86/paravirt: Switch time pvops functions to use static_call()

The time pvops functions are the only ones left which might be
used in 32-bit mode and which return a 64-bit value.

Switch them to use

x86/paravirt: Switch time pvops functions to use static_call()

The time pvops functions are the only ones left which might be
used in 32-bit mode and which return a 64-bit value.

Switch them to use the static_call() mechanism instead of pvops, as
this allows quite some simplification of the pvops implementation.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210311142319.4723-5-jgross@suse.com

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x86/mm/tlb: Flush remote and local TLBs concurrently

To improve TLB shootdown performance, flush the remote and local TLBs
concurrently. Introduce flush_tlb_multi() that does so. Introduce
paravirtu

x86/mm/tlb: Flush remote and local TLBs concurrently

To improve TLB shootdown performance, flush the remote and local TLBs
concurrently. Introduce flush_tlb_multi() that does so. Introduce
paravirtual versions of flush_tlb_multi() for KVM, Xen and hyper-v (Xen
and hyper-v are only compile-tested).

While the updated smp infrastructure is capable of running a function on
a single local core, it is not optimized for this case. The multiple
function calls and the indirect branch introduce some overhead, and
might make local TLB flushes slower than they were before the recent
changes.

Before calling the SMP infrastructure, check if only a local TLB flush
is needed to restore the lost performance in this common case. This
requires to check mm_cpumask() one more time, but unless this mask is
updated very frequently, this should impact performance negatively.

Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Michael Kelley <mikelley@microsoft.com> # Hyper-v parts
Reviewed-by: Juergen Gross <jgross@suse.com> # Xen and paravirt parts
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-5-namit@vmware.com

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x86/pv: Rework arch_local_irq_restore() to not use popf

POPF is a rather expensive operation, so don't use it for restoring
irq flags. Instead, test whether interrupts are enabled in the flags
param

x86/pv: Rework arch_local_irq_restore() to not use popf

POPF is a rather expensive operation, so don't use it for restoring
irq flags. Instead, test whether interrupts are enabled in the flags
parameter and enable interrupts via STI in that case.

This results in the restore_fl paravirt op to be no longer needed.

Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210120135555.32594-7-jgross@suse.com

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x86/xen: Drop USERGS_SYSRET64 paravirt call

USERGS_SYSRET64 is used to return from a syscall via SYSRET, but
a Xen PV guest will nevertheless use the IRET hypercall, as there
is no sysret PV hyperca

x86/xen: Drop USERGS_SYSRET64 paravirt call

USERGS_SYSRET64 is used to return from a syscall via SYSRET, but
a Xen PV guest will nevertheless use the IRET hypercall, as there
is no sysret PV hypercall defined.

So instead of testing all the prerequisites for doing a sysret and
then mangling the stack for Xen PV again for doing an iret just use
the iret exit from the beginning.

This can easily be done via an ALTERNATIVE like it is done for the
sysenter compat case already.

It should be noted that this drops the optimization in Xen for not
restoring a few registers when returning to user mode, but it seems
as if the saved instructions in the kernel more than compensate for
this drop (a kernel build in a Xen PV guest was slightly faster with
this patch applied).

While at it remove the stale sysret32 remnants.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210120135555.32594-6-jgross@suse.com

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