[PATCH v2] target/ppc: Integrate icount to purr, vtb, and tbu40

[PATCH v2] target/ppc: Integrate icount to purr, vtb, and tbu40

[Gustavo Romero]

Currently if option '-icount auto' is passed to the QEMU TCG to enable
counting instructions the VM crashes with the following error report when
Linux runs on it:

qemu-system-ppc64: Bad icount read

This happens because read/write access to the SPRs PURR, VTB, and TBU40
is not integrated to the icount framework.

This commit fixes that issue by making the read/write access of these
SPRs aware of icount framework, adding the proper gen_io_start() calls
before calling the helpers to load/store these SPRs in TCG and ensuring
that the associated TBs end immediately after, accordingly to what's in
docs/devel/tcg-icount.rst.

Signed-off-by: Gustavo Romero <gromero@linux.ibm.com>
---
 target/ppc/translate_init.inc.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/target/ppc/translate_init.inc.c b/target/ppc/translate_init.inc.c
index 7e66822b5d..ccf9ce3441 100644
--- a/target/ppc/translate_init.inc.c
+++ b/target/ppc/translate_init.inc.c
@@ -284,12 +284,24 @@ static void spr_write_atbu(DisasContext *ctx, int sprn, int gprn)
 ATTRIBUTE_UNUSED
 static void spr_read_purr(DisasContext *ctx, int gprn, int sprn)
 {
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_io_start();
+    }
     gen_helper_load_purr(cpu_gpr[gprn], cpu_env);
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_stop_exception(ctx);
+    }
 }
 
 static void spr_write_purr(DisasContext *ctx, int sprn, int gprn)
 {
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_io_start();
+    }
     gen_helper_store_purr(cpu_env, cpu_gpr[gprn]);
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_stop_exception(ctx);
+    }
 }
 
 /* HDECR */
@@ -319,17 +331,35 @@ static void spr_write_hdecr(DisasContext *ctx, int sprn, int gprn)
 
 static void spr_read_vtb(DisasContext *ctx, int gprn, int sprn)
 {
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_io_start();
+    }
     gen_helper_load_vtb(cpu_gpr[gprn], cpu_env);
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_stop_exception(ctx);
+    }
 }
 
 static void spr_write_vtb(DisasContext *ctx, int sprn, int gprn)
 {
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_io_start();
+    }
     gen_helper_store_vtb(cpu_env, cpu_gpr[gprn]);
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_stop_exception(ctx);
+    }
 }
 
 static void spr_write_tbu40(DisasContext *ctx, int sprn, int gprn)
 {
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_io_start();
+    }
     gen_helper_store_tbu40(cpu_env, cpu_gpr[gprn]);
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_stop_exception(ctx);
+    }
 }
 
 #endif
-- 
2.17.1

Re: [PATCH v2] target/ppc: Integrate icount to purr, vtb, and tbu40

[Richard Henderson]

On 8/11/20 8:32 AM, Gustavo Romero wrote:
> Currently if option '-icount auto' is passed to the QEMU TCG to enable
> counting instructions the VM crashes with the following error report when
> Linux runs on it:
> 
> qemu-system-ppc64: Bad icount read
> 
> This happens because read/write access to the SPRs PURR, VTB, and TBU40
> is not integrated to the icount framework.
> 
> This commit fixes that issue by making the read/write access of these
> SPRs aware of icount framework, adding the proper gen_io_start() calls
> before calling the helpers to load/store these SPRs in TCG and ensuring
> that the associated TBs end immediately after, accordingly to what's in
> docs/devel/tcg-icount.rst.
> 
> Signed-off-by: Gustavo Romero <gromero@linux.ibm.com>
> ---
>  target/ppc/translate_init.inc.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

Re: [PATCH v2] target/ppc: Integrate icount to purr, vtb, and tbu40

[David Gibson]

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On Wed, Aug 12, 2020 at 02:33:33PM -0700, Richard Henderson wrote:
> On 8/11/20 8:32 AM, Gustavo Romero wrote:
> > Currently if option '-icount auto' is passed to the QEMU TCG to enable
> > counting instructions the VM crashes with the following error report when
> > Linux runs on it:
> > 
> > qemu-system-ppc64: Bad icount read
> > 
> > This happens because read/write access to the SPRs PURR, VTB, and TBU40
> > is not integrated to the icount framework.
> > 
> > This commit fixes that issue by making the read/write access of these
> > SPRs aware of icount framework, adding the proper gen_io_start() calls
> > before calling the helpers to load/store these SPRs in TCG and ensuring
> > that the associated TBs end immediately after, accordingly to what's in
> > docs/devel/tcg-icount.rst.
> > 
> > Signed-off-by: Gustavo Romero <gromero@linux.ibm.com>
> > ---
> >  target/ppc/translate_init.inc.c | 30 ++++++++++++++++++++++++++++++
> >  1 file changed, 30 insertions(+)
> 
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

Applied to ppc-for-5.2, thanks.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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Re: [PATCH v2] target/ppc: Integrate icount to purr, vtb, and tbu40

[Gustavo Romero]

On 8/12/20 9:03 PM, David Gibson wrote:
> On Wed, Aug 12, 2020 at 02:33:33PM -0700, Richard Henderson wrote:
>> On 8/11/20 8:32 AM, Gustavo Romero wrote:
>>> Currently if option '-icount auto' is passed to the QEMU TCG to enable
>>> counting instructions the VM crashes with the following error report when
>>> Linux runs on it:
>>>
>>> qemu-system-ppc64: Bad icount read
>>>
>>> This happens because read/write access to the SPRs PURR, VTB, and TBU40
>>> is not integrated to the icount framework.
>>>
>>> This commit fixes that issue by making the read/write access of these
>>> SPRs aware of icount framework, adding the proper gen_io_start() calls
>>> before calling the helpers to load/store these SPRs in TCG and ensuring
>>> that the associated TBs end immediately after, accordingly to what's in
>>> docs/devel/tcg-icount.rst.
>>>
>>> Signed-off-by: Gustavo Romero <gromero@linux.ibm.com>
>>> ---
>>>   target/ppc/translate_init.inc.c | 30 ++++++++++++++++++++++++++++++
>>>   1 file changed, 30 insertions(+)
>>
>> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> 
> Applied to ppc-for-5.2, thanks.

Thanks Peter, Richard and David.


Best regards,
Gustavo