To optimize "rep ins" instruction do IO in big chunks ahead of time
instead of doing it only when required during instruction emulation.
Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_emulate.h | 7 +++++++
arch/x86/kvm/emulate.c | 34 ++++++++++++++++++++++++++++++----
2 files changed, 37 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index f74b4ad..da7a711 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -150,6 +150,12 @@ struct fetch_cache {
unsigned long end;
};
+struct read_cache {
+ u8 data[1024];
+ unsigned long pos;
+ unsigned long end;
+};
+
struct decode_cache {
u8 twobyte;
u8 b;
@@ -177,6 +183,7 @@ struct decode_cache {
void *modrm_ptr;
unsigned long modrm_val;
struct fetch_cache fetch;
+ struct read_cache io_read;
};
struct x86_emulate_ctxt {
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 76ed77d..987be2a 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1222,6 +1222,28 @@ done:
return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0;
}
+static int pio_in_emulated(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ unsigned int size, unsigned short port,
+ void *dest, unsigned int count)
+{
+ struct read_cache *mc = &ctxt->decode.io_read;
+
+ if (mc->pos == mc->end) { /* refill pio read ahead */
+ unsigned int n = sizeof(mc->data) / size;
+ n = min(n, count);
+ mc->pos = mc->end = 0;
+ if (!ops->pio_in_emulated(size, port, mc->data, n,
+ ctxt->vcpu))
+ return 0;
+ mc->end = n * size;
+ }
+
+ memcpy(dest, mc->data + mc->pos, size);
+ mc->pos += size;
+ return 1;
+}
+
static u32 desc_limit_scaled(struct desc_struct *desc)
{
u32 limit = get_desc_limit(desc);
@@ -2601,8 +2623,11 @@ special_insn:
kvm_inject_gp(ctxt->vcpu, 0);
goto done;
}
- if (!ops->pio_in_emulated(c->dst.bytes, c->regs[VCPU_REGS_RDX],
- &c->dst.val, 1, ctxt->vcpu))
+ if (c->rep_prefix)
+ ctxt->restart = true;
+ if (!pio_in_emulated(ctxt, ops, c->dst.bytes,
+ c->regs[VCPU_REGS_RDX], &c->dst.val,
+ c->rep_prefix ? c->regs[VCPU_REGS_RCX] : 1))
goto done; /* IO is needed, skip writeback */
register_address_increment(c, &c->regs[VCPU_REGS_RDI],
@@ -2908,8 +2933,9 @@ special_insn:
goto done;
}
if (io_dir_in)
- ops->pio_in_emulated((c->d & ByteOp) ? 1 : c->op_bytes,
- port, &c->dst.val, 1, ctxt->vcpu);
+ pio_in_emulated(ctxt, ops,
+ (c->d & ByteOp) ? 1 : c->op_bytes,
+ port, &c->dst.val, 1);
else
ops->pio_out_emulated((c->d & ByteOp) ? 1 : c->op_bytes,
port, &c->regs[VCPU_REGS_RAX], 1,
--
1.6.5
--
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