On Thu, Nov 23, 2023 at 8:23 AM Ainux Wang <ainux.wang@xxxxxxxxx> wrote:
>
> Huacai Chen <chenhuacai@xxxxxxxxxx> 于2023年11月22日周三 22:22写道：
> >
> > Hi, Yao,
> >
> > On Wed, Nov 22, 2023 at 4:50 PM <wangyao@xxxxxxxxxx> wrote:
> > >
> > > From: Wang Yao <wangyao@xxxxxxxxxx>
> > >
> > > Refer ot UEFI spec v2.10 section 2.3.8 LoongArch Platforms:
> > >
> > > The processor is in the following execution mode during boot service:
> > > ...
> > > The memory is in physical addressing mode. LoongArch architecture
> > > defines two memory access mode, namely direct address translation
> > > mode and mapped address translation mode.
> > >
> > > So need to change MMU translation mode before config direct mapping.
> > From UEFI spec v2.10 section 2.3.8, you can also see "MMU enabled", so
> > PG is already enabled in UEFI.
> >
> > Huacai
> >
> Hi,Huacai,
>
> From LoongArch-Vol1-v1.10-EN.pdf , DA or PG both refer to a mode enabled by MMU,
> Will the UEFI firmware not use DA mode?
> The UEFI spec did not specify the use of DA or PG mode, but the kernel
> must use PG.
In theory you are right, but "MMU" usually means "TLB", including this
case. EFI runtime needs TLB, so UEFI cannot be in DA mode.
Huacai
>
> Best regards,
> Ainux Wang.
> > >
> > > Signed-off-by: Wang Yao <wangyao@xxxxxxxxxx>
> > > ---
> > > drivers/firmware/efi/libstub/loongarch.c | 8 +++++++-
> > > 1 file changed, 7 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/firmware/efi/libstub/loongarch.c b/drivers/firmware/efi/libstub/loongarch.c
> > > index 807cba2693fc..4c0a84c58f5b 100644
> > > --- a/drivers/firmware/efi/libstub/loongarch.c
> > > +++ b/drivers/firmware/efi/libstub/loongarch.c
> > > @@ -49,7 +49,7 @@ efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,
> > > struct exit_boot_struct priv;
> > > unsigned long desc_size;
> > > efi_status_t status;
> > > - u32 desc_ver;
> > > + u32 desc_ver, val;
> > >
> > > status = efi_alloc_virtmap(&priv.runtime_map, &desc_size, &desc_ver);
> > > if (status != EFI_SUCCESS) {
> > > @@ -69,6 +69,12 @@ efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,
> > > priv.runtime_entry_count * desc_size, desc_size,
> > > desc_ver, priv.runtime_map);
> > >
> > > + /* Change address translation mode */
> > > + val = csr_read32(LOONGARCH_CSR_CRMD);
> > > + val &= ~CSR_CRMD_DA;
> > > + val |= CSR_CRMD_PG;
> > > + csr_write32(val, LOONGARCH_CSR_CRMD);
> > > +
> > > /* Config Direct Mapping */
> > > csr_write64(CSR_DMW0_INIT, LOONGARCH_CSR_DMWIN0);
> > > csr_write64(CSR_DMW1_INIT, LOONGARCH_CSR_DMWIN1);
> > > --
> > > 2.27.0
> > >
