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RISC-V: KVM: Prevent HGATP_MODE_BARE passed

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Current 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>
Reviewed-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250821142542.2472079-4-guoren@kernel.org
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Guo Ren (Alibaba DAMO Academy) 2025-08-21 10:25:42 -04:00 committed by Anup Patel
parent 9eac3744db
commit b8d13949a6
2 changed files with 41 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
arch/riscv/kvm/gstage.c
View File

@ -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
}

33
arch/riscv/kvm/main.c
View File

@ -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:
kvm_riscv_nacl_exit();
return -ENODEV;
}
kvm_riscv_gstage_vmid_detect();
@ -135,22 +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());