Commit b8d13949 authored by Guo Ren (Alibaba DAMO Academy)'s avatar Guo Ren (Alibaba DAMO Academy) Committed by Anup Patel
Browse files

RISC-V: KVM: Prevent HGATP_MODE_BARE passed 



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: default avatarTroy Mitchell <troy.mitchell@linux.dev>
Reviewed-by: default avatarNutty Liu <nutty.liu@hotmail.com>
Signed-off-by: default avatarGuo Ren (Alibaba DAMO Academy) <guoren@kernel.org>
Reviewed-by: default avatarFangyu Yu <fangyu.yu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250821142542.2472079-4-guoren@kernel.org


Signed-off-by: default avatarAnup Patel <anup@brainfault.org>
parent 9eac3744

arch/riscv/kvm/gstage.c

+24 −3
Original line number Diff line number Diff line
@@ -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

}

arch/riscv/kvm/main.c

+17 −16
Original line number Diff line number Diff line
@@ -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());