[v3] KVM: PPC: Avoid patching paravirt template code

Currently we patch the whole code include paravirt template code.
This isn't safe for scratch area and has impact to performance.

Signed-off-by: Liu Yu <yu.liu@freescale.com>
---
v2:
exclude the entire template region in the main loop

v3:
make the boundary test more safe

 arch/powerpc/kernel/kvm.c      |   11 ++++++++++-
 arch/powerpc/kernel/kvm_emul.S |    6 ++++++
 2 files changed, 16 insertions(+), 1 deletions(-)

On 02.12.2011, at 07:22, Liu Yu wrote:

> Currently we patch the whole code include paravirt template code.
> This isn't safe for scratch area and has impact to performance.
> 
> Signed-off-by: Liu Yu <yu.liu@freescale.com>

Thanks, applied to kvm-ppc-next. Please CC kvm@vger for KVM related patches in the future.


Alex

> ---
> v2:
> exclude the entire template region in the main loop
> 
> v3:
> make the boundary test more safe
> 
> arch/powerpc/kernel/kvm.c      |   11 ++++++++++-
> arch/powerpc/kernel/kvm_emul.S |    6 ++++++
> 2 files changed, 16 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
> index 3953fbd..55e999d 100644
> --- a/arch/powerpc/kernel/kvm.c
> +++ b/arch/powerpc/kernel/kvm.c
> @@ -665,6 +665,9 @@ static void kvm_check_ins(u32 *inst, u32 features)
> 	}
> }
> 
> +extern u32 kvm_template_start[];
> +extern u32 kvm_template_end[];
> +
> static void kvm_use_magic_page(void)
> {
> 	u32 *p;
> @@ -692,8 +695,14 @@ static void kvm_use_magic_page(void)
> 	 */
> 	local_irq_disable();
> 
> -	for (p = start; p < end; p++)
> +	for (p = start; p < end; p++) {
> +		/* Avoid patching the template code */
> +		if (p >= kvm_template_start && p < kvm_template_end) {
> +			p = kvm_template_end - 1;
> +			continue;
> +		}
> 		kvm_check_ins(p, features);
> +	}
> 
> 	local_irq_enable();
> 
> diff --git a/arch/powerpc/kernel/kvm_emul.S b/arch/powerpc/kernel/kvm_emul.S
> index 801058d..e291cf3 100644
> --- a/arch/powerpc/kernel/kvm_emul.S
> +++ b/arch/powerpc/kernel/kvm_emul.S
> @@ -66,6 +66,9 @@ kvm_hypercall_start:
> 	   shared->critical == r1 and r2 is always != r1 */		\
> 	STL64(r2, KVM_MAGIC_PAGE + KVM_MAGIC_CRITICAL, 0);
> 
> +.global kvm_template_start
> +kvm_template_start:
> +
> .global kvm_emulate_mtmsrd
> kvm_emulate_mtmsrd:
> 
> @@ -350,3 +353,6 @@ kvm_emulate_mtsrin_orig_ins_offs:
> .global kvm_emulate_mtsrin_len
> kvm_emulate_mtsrin_len:
> 	.long (kvm_emulate_mtsrin_end - kvm_emulate_mtsrin) / 4
> +
> +.global kvm_template_end
> +kvm_template_end:
> -- 
> 1.6.4
> 
> 
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