On Wed, Oct 28, 2020 at 8:13 AM Richard Henderson
<richard.hender...@linaro.org> wrote:
>
> On 10/28/20 7:42 AM, Alistair Francis wrote:
> > Add a new MMU mode that includes the current virt mode.
> >
> > Signed-off-by: Alistair Francis <alistair.fran...@wdc.com>
> > ---
> > target/riscv/cpu-param.h | 10 +++++++++-
> > target/riscv/cpu.h | 4 +++-
> > target/riscv/cpu_helper.c | 6 +++++-
> > 3 files changed, 17 insertions(+), 3 deletions(-)
> >
> > diff --git a/target/riscv/cpu-param.h b/target/riscv/cpu-param.h
> > index 664fc1d371..0db6e23140 100644
> > --- a/target/riscv/cpu-param.h
> > +++ b/target/riscv/cpu-param.h
> > @@ -18,6 +18,14 @@
> > # define TARGET_VIRT_ADDR_SPACE_BITS 32 /* sv32 */
> > #endif
> > #define TARGET_PAGE_BITS 12 /* 4 KiB Pages */
> > -#define NB_MMU_MODES 4
> > +/*
> > + * The current MMU Modes are:
> > + * - U mode 0b000
> > + * - S mode 0b001
> > + * - M mode 0b011
> > + * - HU mode 0b100
> > + * - HS mode 0b101
> > + */
> > +#define NB_MMU_MODES 6
> >
> > #endif
> > diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> > index 87b68affa8..5d8e54c426 100644
> > --- a/target/riscv/cpu.h
> > +++ b/target/riscv/cpu.h
> > @@ -363,7 +363,9 @@ void QEMU_NORETURN riscv_raise_exception(CPURISCVState
> > *env,
> > target_ulong riscv_cpu_get_fflags(CPURISCVState *env);
> > void riscv_cpu_set_fflags(CPURISCVState *env, target_ulong);
> >
> > -#define TB_FLAGS_MMU_MASK 3
> > +#define TB_FLAGS_MMU_MASK 7
> > +#define TB_FLAGS_PRIV_MMU_MASK 3
> > +#define TB_FLAGS_PRIV_HYP_ACCESS_MASK (1 << 2)
> > #define TB_FLAGS_MSTATUS_FS MSTATUS_FS
> >
> > typedef CPURISCVState CPUArchState;
> > diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> > index 3eb3a034db..453e4c6d8a 100644
> > --- a/target/riscv/cpu_helper.c
> > +++ b/target/riscv/cpu_helper.c
> > @@ -30,6 +30,10 @@ int riscv_cpu_mmu_index(CPURISCVState *env, bool ifetch)
> > #ifdef CONFIG_USER_ONLY
> > return 0;
> > #else
> > + if (riscv_cpu_virt_enabled(env)) {
> > + return env->priv | TB_FLAGS_PRIV_HYP_ACCESS_MASK;
> > + }
>
> This is wrong. You only want to set this flag in response to one of the
> hypervisor special instructions. This is setting it any time virt is enabled.
Isn't that ok though? I thought this was the correct approach.
Now we have a MMU context for Virtual guests (VS) which have different
contexts to the hypervisor (S). It also then means that when doing the
hypervisor access load/stores we can re-use the existing MMU context
from when the Hypervisor guest was running.
Alistair
>
>
> r~
