>From: "Guo Ren (Alibaba DAMO Academy)" <guoren@xxxxxxxxxx>
>
>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.
This patch helps to detect hardware function missing in advance,
prevent software from entering incorrect logic.
Reviewed-by: Fangyu Yu <fangyu.yu@xxxxxxxxxxxxxxxxx>
>Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren@xxxxxxxxxx>
>---
> 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
