diff options
| author | Sebastian Ene <sebastianene@google.com> | 2026-03-30 13:54:41 +0300 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2026-04-01 18:39:10 +0300 |
| commit | cf6348af645bd8e38758114e6afcc406c5bb515f (patch) | |
| tree | 0f35e38af89a29d669b76047083ea98479d13aee | |
| parent | f338e77383789c0cae23ca3d48adcc5e9e137e3c (diff) | |
| download | linux-cf6348af645bd8e38758114e6afcc406c5bb515f.tar.xz | |
KVM: arm64: Prevent the host from using an smc with imm16 != 0
The ARM Service Calling Convention (SMCCC) specifies that the function
identifier and parameters should be passed in registers, leaving the
16-bit immediate field un-handled in pKVM when an SMC instruction is
trapped.
Since the HVC is a private interface between EL2 and the host,
enforce the host kernel running under pKVM to use an immediate value
of 0 only when using SMCs to make it clear for non-compliant software
talking to Trustzone that we only use SMCCC.
Signed-off-by: Sebastian Ene <sebastianene@google.com>
Reviewed-by: Vincent Donnefort <vdonnefort@google.com>
Link: https://patch.msgid.link/20260330105441.3226904-1-sebastianene@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
| -rw-r--r-- | arch/arm64/kvm/hyp/nvhe/hyp-main.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index e7790097db93..461cf5cb5ac7 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -676,8 +676,14 @@ static void default_host_smc_handler(struct kvm_cpu_context *host_ctxt) static void handle_host_smc(struct kvm_cpu_context *host_ctxt) { DECLARE_REG(u64, func_id, host_ctxt, 0); + u64 esr = read_sysreg_el2(SYS_ESR); bool handled; + if (esr & ESR_ELx_xVC_IMM_MASK) { + cpu_reg(host_ctxt, 0) = SMCCC_RET_NOT_SUPPORTED; + goto exit_skip_instr; + } + func_id &= ~ARM_SMCCC_CALL_HINTS; handled = kvm_host_psci_handler(host_ctxt, func_id); @@ -686,6 +692,7 @@ static void handle_host_smc(struct kvm_cpu_context *host_ctxt) if (!handled) default_host_smc_handler(host_ctxt); +exit_skip_instr: /* SMC was trapped, move ELR past the current PC. */ kvm_skip_host_instr(); } |