[PATCH v6 12/12] x86/paravirt: have only one paravirt patch function

Juergen Gross via Virtualization
2021-03-09T13:48:35Z

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>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
V3:
- remove paravirt_patch_insns() (kernel test robot)
---
arch/x86/include/asm/paravirt_types.h | 19 +------------------
arch/x86/kernel/Makefile | 3 +--
arch/x86/kernel/alternative.c | 2 +-
arch/x86/kernel/paravirt.c | 20 ++------------------
arch/x86/kernel/paravirt_patch.c | 11 -----------
arch/x86/xen/enlighten_pv.c | 1 -
6 files changed, 5 insertions(+), 51 deletions(-)
delete mode 100644 arch/x86/kernel/paravirt_patch.c

diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 588ff14ce969..9d1ddb7b4350 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -68,19 +68,6 @@ struct pv_info {
const char *name;
};

-struct pv_init_ops {
- /*
- * Patch may replace one of the defined code sequences with
- * arbitrary code, subject to the same register constraints.
- * This generally means the code is not free to clobber any
- * registers other than EAX. The patch function should return
- * the number of bytes of code generated, as we nop pad the
- * rest in generic code.
- */
- unsigned (*patch)(u8 type, void *insn_buff,
- unsigned long addr, unsigned len);
-} __no_randomize_layout;
-
#ifdef CONFIG_PARAVIRT_XXL
struct pv_lazy_ops {
/* Set deferred update mode, used for batching operations. */
@@ -276,7 +263,6 @@ struct pv_lock_ops {
* number for each function using the offset which we use to indicate
* what to patch. */
struct paravirt_patch_template {
- struct pv_init_ops init;
struct pv_cpu_ops cpu;
struct pv_irq_ops irq;
struct pv_mmu_ops mmu;
@@ -317,10 +303,7 @@ extern void (*paravirt_iret)(void);
/* Simple instruction patching code. */
#define NATIVE_LABEL(a,x,b) "\n\t.globl " a #x "_" #b "\n" a #x "_" #b ":\n\t"

-unsigned paravirt_patch_default(u8 type, void *insn_buff, unsigned long addr, unsigned len);
-unsigned paravirt_patch_insns(void *insn_buff, unsigned len, const char *start, const char *end);
-
-unsigned native_patch(u8 type, void *insn_buff, unsigned long addr, unsigned len);
+unsigned int paravirt_patch(u8 type, void *insn_buff, unsigned long addr, unsigned int len);

int paravirt_disable_iospace(void);

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 2ddf08351f0b..0704c2a94272 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -35,7 +35,6 @@ KASAN_SANITIZE_sev-es.o := n
KCSAN_SANITIZE := n

OBJECT_FILES_NON_STANDARD_test_nx.o := y
-OBJECT_FILES_NON_STANDARD_paravirt_patch.o := y

ifdef CONFIG_FRAME_POINTER
OBJECT_FILES_NON_STANDARD_ftrace_$(BITS).o := y
@@ -121,7 +120,7 @@ obj-$(CONFIG_AMD_NB) += amd_nb.o
obj-$(CONFIG_DEBUG_NMI_SELFTEST) += nmi_selftest.o

obj-$(CONFIG_KVM_GUEST) += kvm.o kvmclock.o
-obj-$(CONFIG_PARAVIRT) += paravirt.o paravirt_patch.o
+obj-$(CONFIG_PARAVIRT) += paravirt.o
obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= paravirt-spinlocks.o
obj-$(CONFIG_PARAVIRT_CLOCK) += pvclock.o
obj-$(CONFIG_X86_PMEM_LEGACY_DEVICE) += pmem.o
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 1f12901e75f2..cb3eb8c2f50d 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -615,7 +615,7 @@ void __init_or_module apply_paravirt(struct paravirt_patch_site *start,
BUG_ON(p->len > MAX_PATCH_LEN);
/* prep the buffer with the original instructions */
memcpy(insn_buff, p->instr, p->len);
- used = pv_ops.init.patch(p->type, insn_buff, (unsigned long)p->instr, p->len);
+ used = paravirt_patch(p->type, insn_buff, (unsigned long)p->instr, p->len);

BUG_ON(used > p->len);

diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 082954930809..3d7b989ed6be 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -99,8 +99,8 @@ void __init native_pv_lock_init(void)
static_branch_disable(&virt_spin_lock_key);
}

-unsigned paravirt_patch_default(u8 type, void *insn_buff,
- unsigned long addr, unsigned len)
+unsigned int paravirt_patch(u8 type, void *insn_buff, unsigned long addr,
+ unsigned int len)
{
/*
* Neat trick to map patch type back to the call within the
@@ -121,19 +121,6 @@ unsigned paravirt_patch_default(u8 type, void *insn_buff,
return ret;
}

-unsigned paravirt_patch_insns(void *insn_buff, unsigned len,
- const char *start, const char *end)
-{
- unsigned insn_len = end - start;
-
- /* Alternative instruction is too large for the patch site and we cannot continue: */
- BUG_ON(insn_len > len || start == NULL);
-
- memcpy(insn_buff, start, insn_len);
-
- return insn_len;
-}
-
struct static_key paravirt_steal_enabled;
struct static_key paravirt_steal_rq_enabled;

@@ -255,9 +242,6 @@ struct pv_info pv_info = {
#define PTE_IDENT __PV_IS_CALLEE_SAVE(_paravirt_ident_64)

struct paravirt_patch_template pv_ops = {
- /* Init ops. */
- .init.patch = native_patch,
-
/* Cpu ops. */
.cpu.io_delay = native_io_delay,

diff --git a/arch/x86/kernel/paravirt_patch.c b/arch/x86/kernel/paravirt_patch.c
deleted file mode 100644
index 10543dcc8211..000000000000
--- a/arch/x86/kernel/paravirt_patch.c
+++ /dev/null
@@ -1,11 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#include <linux/stringify.h>
-
-#include <asm/paravirt.h>
-#include <asm/asm-offsets.h>
-
-unsigned int native_patch(u8 type, void *insn_buff, unsigned long addr,
- unsigned int len)
-{
- return paravirt_patch_default(type, insn_buff, addr, len);
-}
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 08dca7bebb30..4f18cd9eacd8 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1231,7 +1231,6 @@ asmlinkage __visible void __init xen_start_kernel(void)

/* Install Xen paravirt ops */
pv_info = xen_info;
- pv_ops.init.patch = paravirt_patch_default;
pv_ops.cpu = xen_cpu_ops;
paravirt_iret = xen_iret;
xen_init_irq_ops();