From 92a5199b29f6519aa5f774f4b96dc41954f641d1 Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Tue, 26 Jan 2021 11:36:47 -0600 Subject: [PATCH] sev/i386: Don't allow a system reset under an SEV-ES guest An SEV-ES guest does not allow register state to be altered once it has been measured. When an SEV-ES guest issues a reboot command, Qemu will reset the vCPU state and resume the guest. This will cause failures under SEV-ES. Prevent that from occuring by introducing an arch-specific callback that returns a boolean indicating whether vCPUs are resettable. Cc: Peter Maydell Cc: Aurelien Jarno Cc: Jiaxun Yang Cc: Aleksandar Rikalo Cc: David Gibson Cc: David Hildenbrand Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Tom Lendacky Reviewed-by: Venu Busireddy Message-Id: <1ac39c441b9a3e970e9556e1cc29d0a0814de6fd.1611682609.git.thomas.lendacky@amd.com> Signed-off-by: Paolo Bonzini --- accel/kvm/kvm-all.c | 5 +++++ include/sysemu/cpus.h | 2 ++ include/sysemu/hw_accel.h | 5 +++++ include/sysemu/kvm.h | 10 ++++++++++ softmmu/cpus.c | 5 +++++ softmmu/runstate.c | 3 +++ target/arm/kvm.c | 5 +++++ target/i386/kvm/kvm.c | 6 ++++++ target/mips/kvm.c | 5 +++++ target/ppc/kvm.c | 5 +++++ target/s390x/kvm.c | 5 +++++ 11 files changed, 56 insertions(+) diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index bf61ef4b54..84c943fcdb 100644 --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -2312,6 +2312,11 @@ void kvm_flush_coalesced_mmio_buffer(void) s->coalesced_flush_in_progress = false; } +bool kvm_cpu_check_are_resettable(void) +{ + return kvm_arch_cpu_check_are_resettable(); +} + static void do_kvm_cpu_synchronize_state(CPUState *cpu, run_on_cpu_data arg) { if (!cpu->vcpu_dirty) { diff --git a/include/sysemu/cpus.h b/include/sysemu/cpus.h index 2cd74392e0..868f1192de 100644 --- a/include/sysemu/cpus.h +++ b/include/sysemu/cpus.h @@ -41,6 +41,8 @@ extern int icount_align_option; /* Unblock cpu */ void qemu_cpu_kick_self(void); +bool cpus_are_resettable(void); + void cpu_synchronize_all_states(void); void cpu_synchronize_all_post_reset(void); void cpu_synchronize_all_post_init(void); diff --git a/include/sysemu/hw_accel.h b/include/sysemu/hw_accel.h index ffed6192a3..61672f9b32 100644 --- a/include/sysemu/hw_accel.h +++ b/include/sysemu/hw_accel.h @@ -22,4 +22,9 @@ void cpu_synchronize_post_reset(CPUState *cpu); void cpu_synchronize_post_init(CPUState *cpu); void cpu_synchronize_pre_loadvm(CPUState *cpu); +static inline bool cpu_check_are_resettable(void) +{ + return kvm_enabled() ? kvm_cpu_check_are_resettable() : true; +} + #endif /* QEMU_HW_ACCEL_H */ diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h index c5546bdecc..687c598be9 100644 --- a/include/sysemu/kvm.h +++ b/include/sysemu/kvm.h @@ -541,4 +541,14 @@ int kvm_get_max_memslots(void); /* Notify resamplefd for EOI of specific interrupts. */ void kvm_resample_fd_notify(int gsi); +/** + * kvm_cpu_check_are_resettable - return whether CPUs can be reset + * + * Returns: true: CPUs are resettable + * false: CPUs are not resettable + */ +bool kvm_cpu_check_are_resettable(void); + +bool kvm_arch_cpu_check_are_resettable(void); + #endif diff --git a/softmmu/cpus.c b/softmmu/cpus.c index 112eba9d54..a7ee431187 100644 --- a/softmmu/cpus.c +++ b/softmmu/cpus.c @@ -194,6 +194,11 @@ void cpu_synchronize_pre_loadvm(CPUState *cpu) } } +bool cpus_are_resettable(void) +{ + return cpu_check_are_resettable(); +} + int64_t cpus_get_virtual_clock(void) { /* diff --git a/softmmu/runstate.c b/softmmu/runstate.c index a7fcb603f7..2874417b61 100644 --- a/softmmu/runstate.c +++ b/softmmu/runstate.c @@ -528,6 +528,9 @@ void qemu_system_reset_request(ShutdownCause reason) if (reboot_action == REBOOT_ACTION_SHUTDOWN && reason != SHUTDOWN_CAUSE_SUBSYSTEM_RESET) { shutdown_requested = reason; + } else if (!cpus_are_resettable()) { + error_report("cpus are not resettable, terminating"); + shutdown_requested = reason; } else { reset_requested = reason; } diff --git a/target/arm/kvm.c b/target/arm/kvm.c index ffe186de8d..00e124c812 100644 --- a/target/arm/kvm.c +++ b/target/arm/kvm.c @@ -1045,3 +1045,8 @@ int kvm_arch_msi_data_to_gsi(uint32_t data) { return (data - 32) & 0xffff; } + +bool kvm_arch_cpu_check_are_resettable(void) +{ + return true; +} diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index f56a8536d0..d10667b21b 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -27,6 +27,7 @@ #include "sysemu/kvm_int.h" #include "sysemu/runstate.h" #include "kvm_i386.h" +#include "sev_i386.h" #include "hyperv.h" #include "hyperv-proto.h" @@ -4821,3 +4822,8 @@ bool kvm_has_waitpkg(void) { return has_msr_umwait; } + +bool kvm_arch_cpu_check_are_resettable(void) +{ + return !sev_es_enabled(); +} diff --git a/target/mips/kvm.c b/target/mips/kvm.c index 84fb10ea35..123ec1be7e 100644 --- a/target/mips/kvm.c +++ b/target/mips/kvm.c @@ -1290,3 +1290,8 @@ int mips_kvm_type(MachineState *machine, const char *vm_type) return -1; } + +bool kvm_arch_cpu_check_are_resettable(void) +{ + return true; +} diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c index 0c5056dd5b..298c1f882c 100644 --- a/target/ppc/kvm.c +++ b/target/ppc/kvm.c @@ -2929,3 +2929,8 @@ void kvmppc_set_reg_tb_offset(PowerPCCPU *cpu, int64_t tb_offset) kvm_set_one_reg(cs, KVM_REG_PPC_TB_OFFSET, &tb_offset); } } + +bool kvm_arch_cpu_check_are_resettable(void) +{ + return true; +} diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c index dc27fa36c9..7a892d663d 100644 --- a/target/s390x/kvm.c +++ b/target/s390x/kvm.c @@ -2599,3 +2599,8 @@ void kvm_s390_stop_interrupt(S390CPU *cpu) kvm_s390_vcpu_interrupt(cpu, &irq); } + +bool kvm_arch_cpu_check_are_resettable(void) +{ + return true; +}