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Subject[PATCH 2/2] x86,kvm: remove KVM emulator get_fpu / put_fpu
Date
From: Rik van Riel <riel@redhat.com>

Now that get_fpu and put_fpu do nothing, because the scheduler will
automatically load and restore the guest FPU context for us while we
are in this code (deep inside the vcpu_run main loop), we can get rid
of the get_fpu and put_fpu hooks.

Signed-off-by: Rik van Riel <riel@redhat.com>
Suggested-by: David Hildenbrand <david@redhat.com>
---
arch/x86/include/asm/kvm_emulate.h | 2 --
arch/x86/kvm/emulate.c | 24 ------------------------
arch/x86/kvm/x86.c | 10 ----------
3 files changed, 36 deletions(-)

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index ee23a43386a2..af867fc5ee61 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -214,8 +214,6 @@ struct x86_emulate_ops {
void (*halt)(struct x86_emulate_ctxt *ctxt);
void (*wbinvd)(struct x86_emulate_ctxt *ctxt);
int (*fix_hypercall)(struct x86_emulate_ctxt *ctxt);
- void (*get_fpu)(struct x86_emulate_ctxt *ctxt); /* disables preempt */
- void (*put_fpu)(struct x86_emulate_ctxt *ctxt); /* reenables preempt */
int (*intercept)(struct x86_emulate_ctxt *ctxt,
struct x86_instruction_info *info,
enum x86_intercept_stage stage);
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index d90cdc77e077..9b337bdb59d0 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1046,7 +1046,6 @@ static void fetch_register_operand(struct operand *op)

static void read_sse_reg(struct x86_emulate_ctxt *ctxt, sse128_t *data, int reg)
{
- ctxt->ops->get_fpu(ctxt);
switch (reg) {
case 0: asm("movdqa %%xmm0, %0" : "=m"(*data)); break;
case 1: asm("movdqa %%xmm1, %0" : "=m"(*data)); break;
@@ -1068,13 +1067,11 @@ static void read_sse_reg(struct x86_emulate_ctxt *ctxt, sse128_t *data, int reg)
#endif
default: BUG();
}
- ctxt->ops->put_fpu(ctxt);
}

static void write_sse_reg(struct x86_emulate_ctxt *ctxt, sse128_t *data,
int reg)
{
- ctxt->ops->get_fpu(ctxt);
switch (reg) {
case 0: asm("movdqa %0, %%xmm0" : : "m"(*data)); break;
case 1: asm("movdqa %0, %%xmm1" : : "m"(*data)); break;
@@ -1096,12 +1093,10 @@ static void write_sse_reg(struct x86_emulate_ctxt *ctxt, sse128_t *data,
#endif
default: BUG();
}
- ctxt->ops->put_fpu(ctxt);
}

static void read_mmx_reg(struct x86_emulate_ctxt *ctxt, u64 *data, int reg)
{
- ctxt->ops->get_fpu(ctxt);
switch (reg) {
case 0: asm("movq %%mm0, %0" : "=m"(*data)); break;
case 1: asm("movq %%mm1, %0" : "=m"(*data)); break;
@@ -1113,12 +1108,10 @@ static void read_mmx_reg(struct x86_emulate_ctxt *ctxt, u64 *data, int reg)
case 7: asm("movq %%mm7, %0" : "=m"(*data)); break;
default: BUG();
}
- ctxt->ops->put_fpu(ctxt);
}

static void write_mmx_reg(struct x86_emulate_ctxt *ctxt, u64 *data, int reg)
{
- ctxt->ops->get_fpu(ctxt);
switch (reg) {
case 0: asm("movq %0, %%mm0" : : "m"(*data)); break;
case 1: asm("movq %0, %%mm1" : : "m"(*data)); break;
@@ -1130,7 +1123,6 @@ static void write_mmx_reg(struct x86_emulate_ctxt *ctxt, u64 *data, int reg)
case 7: asm("movq %0, %%mm7" : : "m"(*data)); break;
default: BUG();
}
- ctxt->ops->put_fpu(ctxt);
}

static int em_fninit(struct x86_emulate_ctxt *ctxt)
@@ -1138,9 +1130,7 @@ static int em_fninit(struct x86_emulate_ctxt *ctxt)
if (ctxt->ops->get_cr(ctxt, 0) & (X86_CR0_TS | X86_CR0_EM))
return emulate_nm(ctxt);

- ctxt->ops->get_fpu(ctxt);
asm volatile("fninit");
- ctxt->ops->put_fpu(ctxt);
return X86EMUL_CONTINUE;
}

@@ -1151,9 +1141,7 @@ static int em_fnstcw(struct x86_emulate_ctxt *ctxt)
if (ctxt->ops->get_cr(ctxt, 0) & (X86_CR0_TS | X86_CR0_EM))
return emulate_nm(ctxt);

- ctxt->ops->get_fpu(ctxt);
asm volatile("fnstcw %0": "+m"(fcw));
- ctxt->ops->put_fpu(ctxt);

ctxt->dst.val = fcw;

@@ -1167,9 +1155,7 @@ static int em_fnstsw(struct x86_emulate_ctxt *ctxt)
if (ctxt->ops->get_cr(ctxt, 0) & (X86_CR0_TS | X86_CR0_EM))
return emulate_nm(ctxt);

- ctxt->ops->get_fpu(ctxt);
asm volatile("fnstsw %0": "+m"(fsw));
- ctxt->ops->put_fpu(ctxt);

ctxt->dst.val = fsw;

@@ -3992,12 +3978,8 @@ static int em_fxsave(struct x86_emulate_ctxt *ctxt)
if (rc != X86EMUL_CONTINUE)
return rc;

- ctxt->ops->get_fpu(ctxt);
-
rc = asm_safe("fxsave %[fx]", , [fx] "+m"(fx_state));

- ctxt->ops->put_fpu(ctxt);
-
if (rc != X86EMUL_CONTINUE)
return rc;

@@ -4015,8 +3997,6 @@ static int em_fxrstor(struct x86_emulate_ctxt *ctxt)
if (rc != X86EMUL_CONTINUE)
return rc;

- ctxt->ops->get_fpu(ctxt);
-
size = fxstate_size(ctxt);
if (size < __fxstate_size(16)) {
rc = asm_safe("fxsave %[fx]", , [fx] "+m"(fx_state));
@@ -4037,8 +4017,6 @@ static int em_fxrstor(struct x86_emulate_ctxt *ctxt)
rc = asm_safe("fxrstor %[fx]", : [fx] "m"(fx_state));

out:
- ctxt->ops->put_fpu(ctxt);
-
return rc;
}

@@ -5281,9 +5259,7 @@ static int flush_pending_x87_faults(struct x86_emulate_ctxt *ctxt)
{
int rc;

- ctxt->ops->get_fpu(ctxt);
rc = asm_safe("fwait");
- ctxt->ops->put_fpu(ctxt);

if (unlikely(rc != X86EMUL_CONTINUE))
return emulate_exception(ctxt, MF_VECTOR, 0, false);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index aad5181ed4e9..315d8f2ddd3e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5225,14 +5225,6 @@ static void emulator_halt(struct x86_emulate_ctxt *ctxt)
emul_to_vcpu(ctxt)->arch.halt_request = 1;
}

-static void emulator_get_fpu(struct x86_emulate_ctxt *ctxt)
-{
-}
-
-static void emulator_put_fpu(struct x86_emulate_ctxt *ctxt)
-{
-}
-
static int emulator_intercept(struct x86_emulate_ctxt *ctxt,
struct x86_instruction_info *info,
enum x86_intercept_stage stage)
@@ -5305,8 +5297,6 @@ static const struct x86_emulate_ops emulate_ops = {
.halt = emulator_halt,
.wbinvd = emulator_wbinvd,
.fix_hypercall = emulator_fix_hypercall,
- .get_fpu = emulator_get_fpu,
- .put_fpu = emulator_put_fpu,
.intercept = emulator_intercept,
.get_cpuid = emulator_get_cpuid,
.set_nmi_mask = emulator_set_nmi_mask,
--
2.9.4
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