From b8d13949a6125c0e2e59f0c1f102a38d3c4809d1 Mon Sep 17 00:00:00 2001 From: "Guo Ren (Alibaba DAMO Academy)" Date: Thu, 21 Aug 2025 10:25:42 -0400 Subject: [PATCH] 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: Troy Mitchell Reviewed-by: Nutty Liu Signed-off-by: Guo Ren (Alibaba DAMO Academy) Reviewed-by: Fangyu Yu Link: https://lore.kernel.org/r/20250821142542.2472079-4-guoren@kernel.org Signed-off-by: Anup Patel --- arch/riscv/kvm/gstage.c | 27 ++++++++++++++++++++++++--- arch/riscv/kvm/main.c | 33 +++++++++++++++++---------------- 2 files changed, 41 insertions(+), 19 deletions(-) diff --git a/arch/riscv/kvm/gstage.c b/arch/riscv/kvm/gstage.c index 24c270d6d0e27..b67d60d722c2f 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 67c876de74efb..77dc1655b4423 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: + 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()); -- 2.47.3