The SMC/HVC instructions with an immediate value non-zero are not compliant according to 'SMC calling convention system software document'. Add a validation check in handle_hvc() to avoid malicious HVC calls from VM, and inject an undefined instruction for those calls.
http://infocenter.arm.com/help/topic/com.arm.doc.den0028b/ARM_DEN0028B_SMC_Calling_Convention.pdf Signed-off-by: Shanker Donthineni <shank...@codeaurora.org> --- arch/arm64/include/asm/esr.h | 4 ++++ arch/arm64/kvm/handle_exit.c | 12 +++++++----- 2 files changed, 11 insertions(+), 5 deletions(-) diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h index 8cabd57..fa988e5 100644 --- a/arch/arm64/include/asm/esr.h +++ b/arch/arm64/include/asm/esr.h @@ -107,6 +107,9 @@ #define ESR_ELx_AR (UL(1) << 14) #define ESR_ELx_CM (UL(1) << 8) +/* ISS field definitions for HVC/SVC instruction execution traps */ +#define ESR_HVC_IMMEDIATE(esr) ((esr) & 0xFFFF) + /* ISS field definitions for exceptions taken in to Hyp */ #define ESR_ELx_CV (UL(1) << 24) #define ESR_ELx_COND_SHIFT (20) @@ -114,6 +117,7 @@ #define ESR_ELx_WFx_ISS_WFE (UL(1) << 0) #define ESR_ELx_xVC_IMM_MASK ((1UL << 16) - 1) + /* ESR value templates for specific events */ /* BRK instruction trap from AArch64 state */ diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index 17d8a16..a900dcd 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -42,13 +42,15 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run) kvm_vcpu_hvc_get_imm(vcpu)); vcpu->stat.hvc_exit_stat++; - ret = kvm_psci_call(vcpu); - if (ret < 0) { - kvm_inject_undefined(vcpu); - return 1; + /* HVC immediate value must be zero for all compliant calls */ + if (!ESR_HVC_IMMEDIATE(kvm_vcpu_get_hsr(vcpu))) { + ret = kvm_psci_call(vcpu); + if (ret >= 0) + return ret; } - return ret; + kvm_inject_undefined(vcpu); + return 1; } static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run) -- Qualcomm Datacenter Technologies, Inc. on behalf of the Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project. _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
