[PATCH] KVM: RISC-V: Clear HSTATUS.HU on hypervisor initialization
Yong-Xuan Wang <[email protected]>
| Newsgroups | org.infradead.lists.linux-riscv,org.infradead.lists.kvm-riscv,org.kernel.vger.kvm,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
The RISC-V privileged specification does not mandate HSTATUS reset values, leaving the HU bit potentially set after hardware reset. When HU=1, hypervisor instructions (HLV/HLVX/HSV) can execute in U-mode to access guest memory, which may cause unintended behavior if not explicitly controlled. Clear HSTATUS.HU during KVM initialization to ensure hypervisor instructions are only available in HS-mode, preventing unexpected guest memory access from U-mode code. Signed-off-by: Yong-Xuan Wang <[email protected]> Reviewed-by: Samuel Holland <[email protected]> --- arch/riscv/kvm/main.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c index 85e772588fad..e80a99e93d56 100644 --- a/arch/riscv/kvm/main.c +++ b/arch/riscv/kvm/main.c @@ -47,6 +47,9 @@ static void kvm_riscv_csr_init(void) csr_write(CSR_HCOUNTEREN, 0x02); csr_write(CSR_HVIP, 0); + + /* clear HSTATUS.HU */ + csr_clear(CSR_HSTATUS, HSTATUS_HU); } /* Clear hypervisor CSRs - called during CPU offline and non-retention idle entry */ --- base-commit: b5060a4aa33d7d78a8c1837ab08ef0c81ea96650 change-id: 20260817-hstatus_hu-a1a88a27c7b1 _______________________________________________ linux-riscv mailing list [email protected] http://lists.infradead.org/mailman/listinfo/linux-riscv