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Subject[PATCH v2] KVM: x86: simplify read_emulated
No need split mmio read region into 8-bits pieces since we do it in
emulator_read_write_onepage

Changelog:
Add a WARN_ON to check read-cache overflow

Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
---
arch/x86/kvm/emulate.c | 31 ++++++++++++++-----------------
1 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 97d9a99..e33eb02 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1166,24 +1166,21 @@ static int read_emulated(struct x86_emulate_ctxt *ctxt,
int rc;
struct read_cache *mc = &ctxt->mem_read;

- while (size) {
- int n = min(size, 8u);
- size -= n;
- if (mc->pos < mc->end)
- goto read_cached;
-
- rc = ctxt->ops->read_emulated(ctxt, addr, mc->data + mc->end, n,
- &ctxt->exception);
- if (rc != X86EMUL_CONTINUE)
- return rc;
- mc->end += n;
+ if (mc->pos < mc->end)
+ goto read_cached;

- read_cached:
- memcpy(dest, mc->data + mc->pos, n);
- mc->pos += n;
- dest += n;
- addr += n;
- }
+ WARN_ON((mc->end + size) >= sizeof(mc->data));
+
+ rc = ctxt->ops->read_emulated(ctxt, addr, mc->data + mc->end, size,
+ &ctxt->exception);
+ if (rc != X86EMUL_CONTINUE)
+ return rc;
+
+ mc->end += size;
+
+read_cached:
+ memcpy(dest, mc->data + mc->pos, size);
+ mc->pos += size;
return X86EMUL_CONTINUE;
}

--
1.7.7.6


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