Hi,
On 2019-08-23 08:21, Alistair Francis wrote:
> Let's create a function that tests if floating point support is
> enabled. We can then protect all floating point operations based on if
> they are enabled.
>
> This patch so far doesn't change anything, it's just preparing for the
> Hypervisor support for floating point operations.
>
> Signed-off-by: Alistair Francis <alistair.fran...@wdc.com>
> Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>
> Reviewed-by: Christophe de Dinechin <dinec...@redhat.com>
> Reviewed-by: Chih-Min Chao <chihmin.c...@sifive.com>
> Reviewed-by: Bin Meng <bmeng...@gmail.com>
> ---
> target/riscv/cpu.h | 6 +++++-
> target/riscv/cpu_helper.c | 10 ++++++++++
> target/riscv/csr.c | 20 +++++++++++---------
> 3 files changed, 26 insertions(+), 10 deletions(-)
>
[ snip ]
> diff --git a/target/riscv/csr.c b/target/riscv/csr.c
> index e0d4586760..2789215b5e 100644
> --- a/target/riscv/csr.c
> +++ b/target/riscv/csr.c
[ snip ]
> @@ -307,6 +307,7 @@ static int write_mstatus(CPURISCVState *env, int csrno,
> target_ulong val)
> {
> target_ulong mstatus = env->mstatus;
> target_ulong mask = 0;
> + int dirty;
>
> /* flush tlb on mstatus fields that affect VM */
> if (env->priv_ver <= PRIV_VERSION_1_09_1) {
> @@ -340,8 +341,9 @@ static int write_mstatus(CPURISCVState *env, int csrno,
> target_ulong val)
>
> mstatus = (mstatus & ~mask) | (val & mask);
>
> - int dirty = ((mstatus & MSTATUS_FS) == MSTATUS_FS) |
> - ((mstatus & MSTATUS_XS) == MSTATUS_XS);
> + dirty = (riscv_cpu_fp_enabled(env) &&
> + ((mstatus & MSTATUS_FS) == MSTATUS_FS)) |
> + ((mstatus & MSTATUS_XS) == MSTATUS_XS);
> mstatus = set_field(mstatus, MSTATUS_SD, dirty);
> env->mstatus = mstatus;
This patch, and more precisely the above two hunks broke
qemu-system-riscv64. More precisely, when running a Debian sid system
inside QEMU, sshd hangs during key exchange.
Reverting this commit "fixes" the issue up to the following commit which
breaks things again:
| commit bdce1a5c6d512257f83b6b6831bee2c975643bbd
| Author: Alistair Francis <alistair.fran...@wdc.com>
| Date: Fri Aug 23 08:21:25 2019 -0700
|
| target/riscv: Use TB_FLAGS_MSTATUS_FS for floating point
|
| Use the TB_FLAGS_MSTATUS_FS macro when enabling floating point in the tb
| flags.
|
| Signed-off-by: Alistair Francis <alistair.fran...@wdc.com>
| Reviewed-by: Palmer Dabbelt <pal...@sifive.com>
| Signed-off-by: Palmer Dabbelt <pal...@sifive.com>
I wonder if the issue is related to the fact that MSTATUS_FS and thus
TB_FLAGS_MSTATUS_FS actually consist in 2 bits and are not a simple
flag.
Overall I am able to get QEMU v4.2 working again by applying the
following patch:
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index e59343e13c..f0ff57e27a 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -295,7 +295,7 @@ static inline void cpu_get_tb_cpu_state(CPURISCVState *env,
target_ulong *pc,
#else
*flags = cpu_mmu_index(env, 0);
if (riscv_cpu_fp_enabled(env)) {
- *flags |= TB_FLAGS_MSTATUS_FS;
+ *flags |= env->mstatus & MSTATUS_FS;
}
#endif
}
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index da02f9f0b1..1754c6c575 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -307,7 +307,6 @@ static int write_mstatus(CPURISCVState *env, int csrno,
target_ulong val)
{
target_ulong mstatus = env->mstatus;
target_ulong mask = 0;
- int dirty;
/* flush tlb on mstatus fields that affect VM */
if (env->priv_ver <= PRIV_VERSION_1_09_1) {
@@ -341,9 +340,8 @@ static int write_mstatus(CPURISCVState *env, int csrno,
target_ulong val)
mstatus = (mstatus & ~mask) | (val & mask);
- dirty = (riscv_cpu_fp_enabled(env) &&
- ((mstatus & MSTATUS_FS) == MSTATUS_FS)) |
- ((mstatus & MSTATUS_XS) == MSTATUS_XS);
+ int dirty = ((mstatus & MSTATUS_FS) == MSTATUS_FS) |
+ ((mstatus & MSTATUS_XS) == MSTATUS_XS);
mstatus = set_field(mstatus, MSTATUS_SD, dirty);
env->mstatus = mstatus;
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurel...@aurel32.net http://www.aurel32.net
