[PATCH V4 RESEND 0/3] Fixup & optimize hgatp mode & vmid detect functions

[PATCH V4 RESEND 0/3] Fixup & optimize hgatp mode & vmid detect functions

[guoren]

From: "Guo Ren (Alibaba DAMO Academy)" <guoren@kernel.org>

Here are serval fixup & optmizitions for hgatp detect according
to the RISC-V Privileged Architecture Spec.

---
Changes in v4:
 - Involve ("RISC-V: KVM: Prevent HGATP_MODE_BARE passed"), which
   explain why gstage_mode_detect needs reset HGATP to zero.
 - RESEND for wrong mailing thread.
 
Changes in v3:
 - Add "Fixes" tag.
 - Involve("RISC-V: KVM: Remove unnecessary HGATP csr_read"), which
   depends on patch 1.

Changes in v2:
 - Fixed build error since kvm_riscv_gstage_mode() has been modified.
---

Fangyu Yu (1):
  RISC-V: KVM: Write hgatp register with valid mode bits

Guo Ren (Alibaba DAMO Academy) (2):
  RISC-V: KVM: Remove unnecessary HGATP csr_read
  RISC-V: KVM: Prevent HGATP_MODE_BARE passed

 arch/riscv/kvm/gstage.c | 27 ++++++++++++++++++++++++---
 arch/riscv/kvm/main.c   | 35 +++++++++++++++++------------------
 arch/riscv/kvm/vmid.c   |  8 +++-----
 3 files changed, 44 insertions(+), 26 deletions(-)

-- 
2.40.1


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[PATCH V4 RESEND 1/3] RISC-V: KVM: Write hgatp register with valid mode bits

[guoren]

From: Fangyu Yu <fangyu.yu@linux.alibaba.com>

According to the RISC-V Privileged Architecture Spec, when MODE=Bare
is selected,software must write zero to the remaining fields of hgatp.

We have detected the valid mode supported by the HW before, So using a
valid mode to detect how many vmid bits are supported.

Fixes: fd7bb4a251df ("RISC-V: KVM: Implement VMID allocator")
Reviewed-by: Nutty Liu <nutty.liu@hotmail.com>
Reviewed-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Reviewed-by: Guo Ren (Alibaba DAMO Academy) <guoren@kernel.org>
Signed-off-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren@kernel.org>
---
 arch/riscv/kvm/vmid.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kvm/vmid.c b/arch/riscv/kvm/vmid.c
index 3b426c800480..5f33625f4070 100644
--- a/arch/riscv/kvm/vmid.c
+++ b/arch/riscv/kvm/vmid.c
@@ -14,6 +14,7 @@
 #include <linux/smp.h>
 #include <linux/kvm_host.h>
 #include <asm/csr.h>
+#include <asm/kvm_mmu.h>
 #include <asm/kvm_tlb.h>
 #include <asm/kvm_vmid.h>
 
@@ -28,7 +29,7 @@ void __init kvm_riscv_gstage_vmid_detect(void)
 
 	/* Figure-out number of VMID bits in HW */
 	old = csr_read(CSR_HGATP);
-	csr_write(CSR_HGATP, old | HGATP_VMID);
+	csr_write(CSR_HGATP, (kvm_riscv_gstage_mode << HGATP_MODE_SHIFT) | HGATP_VMID);
 	vmid_bits = csr_read(CSR_HGATP);
 	vmid_bits = (vmid_bits & HGATP_VMID) >> HGATP_VMID_SHIFT;
 	vmid_bits = fls_long(vmid_bits);
-- 
2.40.1


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[PATCH V4 RESEND 2/3] RISC-V: KVM: Remove unnecessary HGATP csr_read

[guoren]

From: "Guo Ren (Alibaba DAMO Academy)" <guoren@kernel.org>

The HGATP has been set to zero in gstage_mode_detect(), so there
is no need to save the old context. Unify the code convention
with gstage_mode_detect().

Reviewed-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
Signed-off-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren@kernel.org>
---
 arch/riscv/kvm/vmid.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/riscv/kvm/vmid.c b/arch/riscv/kvm/vmid.c
index 5f33625f4070..abb1c2bf2542 100644
--- a/arch/riscv/kvm/vmid.c
+++ b/arch/riscv/kvm/vmid.c
@@ -25,15 +25,12 @@ static DEFINE_SPINLOCK(vmid_lock);
 
 void __init kvm_riscv_gstage_vmid_detect(void)
 {
-	unsigned long old;
-
 	/* Figure-out number of VMID bits in HW */
-	old = csr_read(CSR_HGATP);
 	csr_write(CSR_HGATP, (kvm_riscv_gstage_mode << HGATP_MODE_SHIFT) | HGATP_VMID);
 	vmid_bits = csr_read(CSR_HGATP);
 	vmid_bits = (vmid_bits & HGATP_VMID) >> HGATP_VMID_SHIFT;
 	vmid_bits = fls_long(vmid_bits);
-	csr_write(CSR_HGATP, old);
+	csr_write(CSR_HGATP, 0);
 
 	/* We polluted local TLB so flush all guest TLB */
 	kvm_riscv_local_hfence_gvma_all();
-- 
2.40.1


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[PATCH V4 RESEND 3/3] RISC-V: KVM: Prevent HGATP_MODE_BARE passed

[guoren]

From: "Guo Ren (Alibaba DAMO Academy)" <guoren@kernel.org>

urrent kvm_riscv_gstage_mode_detect() assumes H-extension must
have HGATP_MODE_SV39X4/SV32X4 at least, but the spec allows
H-extension with HGATP_MODE_BARE alone. The KVM depends on
!HGATP_MODE_BARE at least, so enhance the gstage-mode-detect
to block HGATP_MODE_BARE.

Move gstage-mode-check closer to gstage-mode-detect to prevent
unnecessary init.

Reviewed-by: Troy Mitchell <troy.mitchell@linux.dev>
Reviewed-by: Nutty Liu <nutty.liu@hotmail.com>
Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren@kernel.org>
---
 arch/riscv/kvm/gstage.c | 27 ++++++++++++++++++++++++---
 arch/riscv/kvm/main.c   | 35 +++++++++++++++++------------------
 2 files changed, 41 insertions(+), 21 deletions(-)

diff --git a/arch/riscv/kvm/gstage.c b/arch/riscv/kvm/gstage.c
index 24c270d6d0e2..b67d60d722c2 100644
--- a/arch/riscv/kvm/gstage.c
+++ b/arch/riscv/kvm/gstage.c
@@ -321,7 +321,7 @@ void __init kvm_riscv_gstage_mode_detect(void)
 	if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV57X4) {
 		kvm_riscv_gstage_mode = HGATP_MODE_SV57X4;
 		kvm_riscv_gstage_pgd_levels = 5;
-		goto skip_sv48x4_test;
+		goto done;
 	}
 
 	/* Try Sv48x4 G-stage mode */
@@ -329,10 +329,31 @@ void __init kvm_riscv_gstage_mode_detect(void)
 	if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV48X4) {
 		kvm_riscv_gstage_mode = HGATP_MODE_SV48X4;
 		kvm_riscv_gstage_pgd_levels = 4;
+		goto done;
 	}
-skip_sv48x4_test:
 
+	/* Try Sv39x4 G-stage mode */
+	csr_write(CSR_HGATP, HGATP_MODE_SV39X4 << HGATP_MODE_SHIFT);
+	if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV39X4) {
+		kvm_riscv_gstage_mode = HGATP_MODE_SV39X4;
+		kvm_riscv_gstage_pgd_levels = 3;
+		goto done;
+	}
+#else /* CONFIG_32BIT */
+	/* Try Sv32x4 G-stage mode */
+	csr_write(CSR_HGATP, HGATP_MODE_SV32X4 << HGATP_MODE_SHIFT);
+	if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV32X4) {
+		kvm_riscv_gstage_mode = HGATP_MODE_SV32X4;
+		kvm_riscv_gstage_pgd_levels = 2;
+		goto done;
+	}
+#endif
+
+	/* KVM depends on !HGATP_MODE_OFF */
+	kvm_riscv_gstage_mode = HGATP_MODE_OFF;
+	kvm_riscv_gstage_pgd_levels = 0;
+
+done:
 	csr_write(CSR_HGATP, 0);
 	kvm_riscv_local_hfence_gvma_all();
-#endif
 }
diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
index 67c876de74ef..8ee7aaa74ddc 100644
--- a/arch/riscv/kvm/main.c
+++ b/arch/riscv/kvm/main.c
@@ -93,6 +93,23 @@ static int __init riscv_kvm_init(void)
 		return rc;
 
 	kvm_riscv_gstage_mode_detect();
+	switch (kvm_riscv_gstage_mode) {
+	case HGATP_MODE_SV32X4:
+		str = "Sv32x4";
+		break;
+	case HGATP_MODE_SV39X4:
+		str = "Sv39x4";
+		break;
+	case HGATP_MODE_SV48X4:
+		str = "Sv48x4";
+		break;
+	case HGATP_MODE_SV57X4:
+		str = "Sv57x4";
+		break;
+	default:
+		return -ENODEV;
+	}
+	kvm_info("using %s G-stage page table format\n", str);
 
 	kvm_riscv_gstage_vmid_detect();
 
@@ -135,24 +152,6 @@ static int __init riscv_kvm_init(void)
 			 (rc) ? slist : "no features");
 	}
 
-	switch (kvm_riscv_gstage_mode) {
-	case HGATP_MODE_SV32X4:
-		str = "Sv32x4";
-		break;
-	case HGATP_MODE_SV39X4:
-		str = "Sv39x4";
-		break;
-	case HGATP_MODE_SV48X4:
-		str = "Sv48x4";
-		break;
-	case HGATP_MODE_SV57X4:
-		str = "Sv57x4";
-		break;
-	default:
-		return -ENODEV;
-	}
-	kvm_info("using %s G-stage page table format\n", str);
-
 	kvm_info("VMID %ld bits available\n", kvm_riscv_gstage_vmid_bits());
 
 	if (kvm_riscv_aia_available())
-- 
2.40.1


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Re: [PATCH V4 RESEND 0/3] Fixup & optimize hgatp mode & vmid detect functions

[Guo Ren]

Hi Anup,

Ping..., hope for feedback.

On Thu, Aug 21, 2025 at 10:26 PM <guoren@kernel.org> wrote:
>
> From: "Guo Ren (Alibaba DAMO Academy)" <guoren@kernel.org>
>
> Here are serval fixup & optmizitions for hgatp detect according
> to the RISC-V Privileged Architecture Spec.
>
> ---
> Changes in v4:
>  - Involve ("RISC-V: KVM: Prevent HGATP_MODE_BARE passed"), which
>    explain why gstage_mode_detect needs reset HGATP to zero.
>  - RESEND for wrong mailing thread.
>
> Changes in v3:
>  - Add "Fixes" tag.
>  - Involve("RISC-V: KVM: Remove unnecessary HGATP csr_read"), which
>    depends on patch 1.
>
> Changes in v2:
>  - Fixed build error since kvm_riscv_gstage_mode() has been modified.
> ---
>
> Fangyu Yu (1):
>   RISC-V: KVM: Write hgatp register with valid mode bits
>
> Guo Ren (Alibaba DAMO Academy) (2):
>   RISC-V: KVM: Remove unnecessary HGATP csr_read
>   RISC-V: KVM: Prevent HGATP_MODE_BARE passed
>
>  arch/riscv/kvm/gstage.c | 27 ++++++++++++++++++++++++---
>  arch/riscv/kvm/main.c   | 35 +++++++++++++++++------------------
>  arch/riscv/kvm/vmid.c   |  8 +++-----
>  3 files changed, 44 insertions(+), 26 deletions(-)
>
> --
> 2.40.1
>


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Re: [PATCH V4 RESEND 3/3] RISC-V: KVM: Prevent HGATP_MODE_BARE passed

[Anup Patel]

On Thu, Aug 21, 2025 at 7:56 PM <guoren@kernel.org> wrote:
>
> From: "Guo Ren (Alibaba DAMO Academy)" <guoren@kernel.org>
>
> urrent kvm_riscv_gstage_mode_detect() assumes H-extension must

s/urrent/Current/

> have HGATP_MODE_SV39X4/SV32X4 at least, but the spec allows
> H-extension with HGATP_MODE_BARE alone. The KVM depends on
> !HGATP_MODE_BARE at least, so enhance the gstage-mode-detect
> to block HGATP_MODE_BARE.
>
> Move gstage-mode-check closer to gstage-mode-detect to prevent
> unnecessary init.
>
> Reviewed-by: Troy Mitchell <troy.mitchell@linux.dev>
> Reviewed-by: Nutty Liu <nutty.liu@hotmail.com>
> Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren@kernel.org>
> ---
>  arch/riscv/kvm/gstage.c | 27 ++++++++++++++++++++++++---
>  arch/riscv/kvm/main.c   | 35 +++++++++++++++++------------------
>  2 files changed, 41 insertions(+), 21 deletions(-)
>
> diff --git a/arch/riscv/kvm/gstage.c b/arch/riscv/kvm/gstage.c
> index 24c270d6d0e2..b67d60d722c2 100644
> --- a/arch/riscv/kvm/gstage.c
> +++ b/arch/riscv/kvm/gstage.c
> @@ -321,7 +321,7 @@ void __init kvm_riscv_gstage_mode_detect(void)
>         if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV57X4) {
>                 kvm_riscv_gstage_mode = HGATP_MODE_SV57X4;
>                 kvm_riscv_gstage_pgd_levels = 5;
> -               goto skip_sv48x4_test;
> +               goto done;
>         }
>
>         /* Try Sv48x4 G-stage mode */
> @@ -329,10 +329,31 @@ void __init kvm_riscv_gstage_mode_detect(void)
>         if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV48X4) {
>                 kvm_riscv_gstage_mode = HGATP_MODE_SV48X4;
>                 kvm_riscv_gstage_pgd_levels = 4;
> +               goto done;
>         }
> -skip_sv48x4_test:
>
> +       /* Try Sv39x4 G-stage mode */
> +       csr_write(CSR_HGATP, HGATP_MODE_SV39X4 << HGATP_MODE_SHIFT);
> +       if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV39X4) {
> +               kvm_riscv_gstage_mode = HGATP_MODE_SV39X4;
> +               kvm_riscv_gstage_pgd_levels = 3;
> +               goto done;
> +       }
> +#else /* CONFIG_32BIT */
> +       /* Try Sv32x4 G-stage mode */
> +       csr_write(CSR_HGATP, HGATP_MODE_SV32X4 << HGATP_MODE_SHIFT);
> +       if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV32X4) {
> +               kvm_riscv_gstage_mode = HGATP_MODE_SV32X4;
> +               kvm_riscv_gstage_pgd_levels = 2;
> +               goto done;
> +       }
> +#endif
> +
> +       /* KVM depends on !HGATP_MODE_OFF */
> +       kvm_riscv_gstage_mode = HGATP_MODE_OFF;
> +       kvm_riscv_gstage_pgd_levels = 0;
> +
> +done:
>         csr_write(CSR_HGATP, 0);
>         kvm_riscv_local_hfence_gvma_all();
> -#endif
>  }
> diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
> index 67c876de74ef..8ee7aaa74ddc 100644
> --- a/arch/riscv/kvm/main.c
> +++ b/arch/riscv/kvm/main.c
> @@ -93,6 +93,23 @@ static int __init riscv_kvm_init(void)
>                 return rc;
>
>         kvm_riscv_gstage_mode_detect();
> +       switch (kvm_riscv_gstage_mode) {
> +       case HGATP_MODE_SV32X4:
> +               str = "Sv32x4";
> +               break;
> +       case HGATP_MODE_SV39X4:
> +               str = "Sv39x4";
> +               break;
> +       case HGATP_MODE_SV48X4:
> +               str = "Sv48x4";
> +               break;
> +       case HGATP_MODE_SV57X4:
> +               str = "Sv57x4";
> +               break;
> +       default:

Need kvm_riscv_nacl_exit() here.

> +               return -ENODEV;
> +       }
> +       kvm_info("using %s G-stage page table format\n", str);

Moving the kvm_info() over here now prints G-stage mode
before announcing availablity of h-extension which looks odd.
It's better to keep kvm_info() in the same location and only
move the switch-case.

>
>         kvm_riscv_gstage_vmid_detect();
>
> @@ -135,24 +152,6 @@ static int __init riscv_kvm_init(void)
>                          (rc) ? slist : "no features");
>         }
>
> -       switch (kvm_riscv_gstage_mode) {
> -       case HGATP_MODE_SV32X4:
> -               str = "Sv32x4";
> -               break;
> -       case HGATP_MODE_SV39X4:
> -               str = "Sv39x4";
> -               break;
> -       case HGATP_MODE_SV48X4:
> -               str = "Sv48x4";
> -               break;
> -       case HGATP_MODE_SV57X4:
> -               str = "Sv57x4";
> -               break;
> -       default:
> -               return -ENODEV;
> -       }
> -       kvm_info("using %s G-stage page table format\n", str);
> -
>         kvm_info("VMID %ld bits available\n", kvm_riscv_gstage_vmid_bits());
>
>         if (kvm_riscv_aia_available())
> --
> 2.40.1
>

Otherwise, this looks good to me.

I will take care of minor comments mentioned above at the
time of merging this series.

Regards,
Anup

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Re: [PATCH V4 RESEND 0/3] Fixup & optimize hgatp mode & vmid detect functions

[Anup Patel]

On Thu, Aug 21, 2025 at 7:56 PM <guoren@kernel.org> wrote:
>
> From: "Guo Ren (Alibaba DAMO Academy)" <guoren@kernel.org>
>
> Here are serval fixup & optmizitions for hgatp detect according
> to the RISC-V Privileged Architecture Spec.
>
> ---
> Changes in v4:
>  - Involve ("RISC-V: KVM: Prevent HGATP_MODE_BARE passed"), which
>    explain why gstage_mode_detect needs reset HGATP to zero.
>  - RESEND for wrong mailing thread.
>
> Changes in v3:
>  - Add "Fixes" tag.
>  - Involve("RISC-V: KVM: Remove unnecessary HGATP csr_read"), which
>    depends on patch 1.
>
> Changes in v2:
>  - Fixed build error since kvm_riscv_gstage_mode() has been modified.
> ---
>
> Fangyu Yu (1):
>   RISC-V: KVM: Write hgatp register with valid mode bits
>
> Guo Ren (Alibaba DAMO Academy) (2):
>   RISC-V: KVM: Remove unnecessary HGATP csr_read
>   RISC-V: KVM: Prevent HGATP_MODE_BARE passed
>
>  arch/riscv/kvm/gstage.c | 27 ++++++++++++++++++++++++---
>  arch/riscv/kvm/main.c   | 35 +++++++++++++++++------------------
>  arch/riscv/kvm/vmid.c   |  8 +++-----
>  3 files changed, 44 insertions(+), 26 deletions(-)
>
> --
> 2.40.1
>

Queued this series for Linux-6.18

Regards,
Anup

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Re: [PATCH V4 RESEND 3/3] RISC-V: KVM: Prevent HGATP_MODE_BARE passed

[Guo Ren]

On Fri, Sep 5, 2025 at 2:51 PM Anup Patel <anup@brainfault.org> wrote:
>
> On Thu, Aug 21, 2025 at 7:56 PM <guoren@kernel.org> wrote:
> >
> > From: "Guo Ren (Alibaba DAMO Academy)" <guoren@kernel.org>
> >
> > urrent kvm_riscv_gstage_mode_detect() assumes H-extension must
>
> s/urrent/Current/
Oh, my fault about copy & paste.


>
> > have HGATP_MODE_SV39X4/SV32X4 at least, but the spec allows
> > H-extension with HGATP_MODE_BARE alone. The KVM depends on
> > !HGATP_MODE_BARE at least, so enhance the gstage-mode-detect
> > to block HGATP_MODE_BARE.
> >
> > Move gstage-mode-check closer to gstage-mode-detect to prevent
> > unnecessary init.
> >
> > Reviewed-by: Troy Mitchell <troy.mitchell@linux.dev>
> > Reviewed-by: Nutty Liu <nutty.liu@hotmail.com>
> > Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren@kernel.org>
> > ---
> >  arch/riscv/kvm/gstage.c | 27 ++++++++++++++++++++++++---
> >  arch/riscv/kvm/main.c   | 35 +++++++++++++++++------------------
> >  2 files changed, 41 insertions(+), 21 deletions(-)
> >
> > diff --git a/arch/riscv/kvm/gstage.c b/arch/riscv/kvm/gstage.c
> > index 24c270d6d0e2..b67d60d722c2 100644
> > --- a/arch/riscv/kvm/gstage.c
> > +++ b/arch/riscv/kvm/gstage.c
> > @@ -321,7 +321,7 @@ void __init kvm_riscv_gstage_mode_detect(void)
> >         if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV57X4) {
> >                 kvm_riscv_gstage_mode = HGATP_MODE_SV57X4;
> >                 kvm_riscv_gstage_pgd_levels = 5;
> > -               goto skip_sv48x4_test;
> > +               goto done;
> >         }
> >
> >         /* Try Sv48x4 G-stage mode */
> > @@ -329,10 +329,31 @@ void __init kvm_riscv_gstage_mode_detect(void)
> >         if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV48X4) {
> >                 kvm_riscv_gstage_mode = HGATP_MODE_SV48X4;
> >                 kvm_riscv_gstage_pgd_levels = 4;
> > +               goto done;
> >         }
> > -skip_sv48x4_test:
> >
> > +       /* Try Sv39x4 G-stage mode */
> > +       csr_write(CSR_HGATP, HGATP_MODE_SV39X4 << HGATP_MODE_SHIFT);
> > +       if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV39X4) {
> > +               kvm_riscv_gstage_mode = HGATP_MODE_SV39X4;
> > +               kvm_riscv_gstage_pgd_levels = 3;
> > +               goto done;
> > +       }
> > +#else /* CONFIG_32BIT */
> > +       /* Try Sv32x4 G-stage mode */
> > +       csr_write(CSR_HGATP, HGATP_MODE_SV32X4 << HGATP_MODE_SHIFT);
> > +       if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV32X4) {
> > +               kvm_riscv_gstage_mode = HGATP_MODE_SV32X4;
> > +               kvm_riscv_gstage_pgd_levels = 2;
> > +               goto done;
> > +       }
> > +#endif
> > +
> > +       /* KVM depends on !HGATP_MODE_OFF */
> > +       kvm_riscv_gstage_mode = HGATP_MODE_OFF;
> > +       kvm_riscv_gstage_pgd_levels = 0;
> > +
> > +done:
> >         csr_write(CSR_HGATP, 0);
> >         kvm_riscv_local_hfence_gvma_all();
> > -#endif
> >  }
> > diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
> > index 67c876de74ef..8ee7aaa74ddc 100644
> > --- a/arch/riscv/kvm/main.c
> > +++ b/arch/riscv/kvm/main.c
> > @@ -93,6 +93,23 @@ static int __init riscv_kvm_init(void)
> >                 return rc;
> >
> >         kvm_riscv_gstage_mode_detect();
> > +       switch (kvm_riscv_gstage_mode) {
> > +       case HGATP_MODE_SV32X4:
> > +               str = "Sv32x4";
> > +               break;
> > +       case HGATP_MODE_SV39X4:
> > +               str = "Sv39x4";
> > +               break;
> > +       case HGATP_MODE_SV48X4:
> > +               str = "Sv48x4";
> > +               break;
> > +       case HGATP_MODE_SV57X4:
> > +               str = "Sv57x4";
> > +               break;
> > +       default:
>
> Need kvm_riscv_nacl_exit() here.
Yes, it's another legacy problem, which lacks:
        kvm_riscv_aia_exit();
        kvm_riscv_nacl_exit();

After we move it up, it still needs:
        kvm_riscv_nacl_exit();

I'm okay with it being fixed in this patch.

>
> > +               return -ENODEV;
> > +       }
> > +       kvm_info("using %s G-stage page table format\n", str);
>
> Moving the kvm_info() over here now prints G-stage mode
> before announcing availablity of h-extension which looks odd.
> It's better to keep kvm_info() in the same location and only
> move the switch-case.
okay.

>
> >
> >         kvm_riscv_gstage_vmid_detect();
> >
> > @@ -135,24 +152,6 @@ static int __init riscv_kvm_init(void)
> >                          (rc) ? slist : "no features");
> >         }
> >
> > -       switch (kvm_riscv_gstage_mode) {
> > -       case HGATP_MODE_SV32X4:
> > -               str = "Sv32x4";
> > -               break;
> > -       case HGATP_MODE_SV39X4:
> > -               str = "Sv39x4";
> > -               break;
> > -       case HGATP_MODE_SV48X4:
> > -               str = "Sv48x4";
> > -               break;
> > -       case HGATP_MODE_SV57X4:
> > -               str = "Sv57x4";
> > -               break;
> > -       default:
> > -               return -ENODEV;
> > -       }
> > -       kvm_info("using %s G-stage page table format\n", str);
> > -
> >         kvm_info("VMID %ld bits available\n", kvm_riscv_gstage_vmid_bits());
> >
> >         if (kvm_riscv_aia_available())
> > --
> > 2.40.1
> >
>
> Otherwise, this looks good to me.
>
> I will take care of minor comments mentioned above at the
> time of merging this series.
Thx for taking care. Nice!

--
Best Regards
 Guo Ren

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