VMware products handle hypercalls in userspace. Give KVM the ability to run VMware guests unmodified by fowarding all hypercalls to the userspace.
Enabling of the KVM_CAP_X86_VMWARE_HYPERCALL_ENABLE capability turns the feature on - it's off by default. This allows vmx's built on top of KVM to support VMware specific hypercalls.
Signed-off-by: Zack Rusin zack.rusin@broadcom.com Cc: Doug Covelli doug.covelli@broadcom.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Jonathan Corbet corbet@lwn.net Cc: Sean Christopherson seanjc@google.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Ingo Molnar mingo@redhat.com Cc: Borislav Petkov bp@alien8.de Cc: Dave Hansen dave.hansen@linux.intel.com Cc: x86@kernel.org Cc: "H. Peter Anvin" hpa@zytor.com Cc: Shuah Khan shuah@kernel.org Cc: Namhyung Kim namhyung@kernel.org Cc: Arnaldo Carvalho de Melo acme@redhat.com Cc: Isaku Yamahata isaku.yamahata@intel.com Cc: Joel Stanley joel@jms.id.au Cc: Zack Rusin zack.rusin@broadcom.com Cc: kvm@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-kselftest@vger.kernel.org --- Documentation/virt/kvm/api.rst | 41 +++++++++++++++++++++++++++++---- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/x86.c | 33 ++++++++++++++++++++++++++ include/uapi/linux/kvm.h | 1 + 4 files changed, 72 insertions(+), 4 deletions(-)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 33ef3cc785e4..5a8c7922f64f 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6601,10 +6601,11 @@ to the byte array. .. note::
For KVM_EXIT_IO, KVM_EXIT_MMIO, KVM_EXIT_OSI, KVM_EXIT_PAPR, KVM_EXIT_XEN, - KVM_EXIT_EPR, KVM_EXIT_X86_RDMSR and KVM_EXIT_X86_WRMSR the corresponding - operations are complete (and guest state is consistent) only after userspace - has re-entered the kernel with KVM_RUN. The kernel side will first finish - incomplete operations and then check for pending signals. + KVM_EXIT_EPR, KVM_EXIT_HYPERCALL, KVM_EXIT_X86_RDMSR and KVM_EXIT_X86_WRMSR + the corresponding operations are complete (and guest state is consistent) + only after userspace has re-entered the kernel with KVM_RUN. The kernel + side will first finish incomplete operations and then check for pending + signals.
The pending state of the operation is not preserved in state which is visible to userspace, thus userspace should ensure that the operation is @@ -8201,6 +8202,38 @@ default value for it is set via the kvm.enable_vmware_backdoor kernel parameter (false when not set). Must be set before any VCPUs have been created.
+7.38 KVM_CAP_X86_VMWARE_HYPERCALL +--------------------------------- + +:Architectures: x86 +:Parameters: args[0] whether the feature should be enabled or not +:Returns: 0 on success. + +Capability allows userspace to handle hypercalls. When enabled +whenever the vcpu has executed a VMCALL(Intel) or a VMMCALL(AMD) +instruction kvm will exit to userspace with KVM_EXIT_HYPERCALL. + +On exit the hypercall structure of the kvm_run structure will +look as follows: + +:: + /* KVM_EXIT_HYPERCALL */ + struct { + __u64 nr; // rax + __u64 args[6]; // rbx, rcx, rdx, rsi, rdi, rbp + __u64 ret; // cpl, whatever userspace + // sets this to on return will be + // written to the rax + __u64 flags; // KVM_EXIT_HYPERCALL_LONG_MODE if + // the hypercall was executed in + // 64bit mode, 0 otherwise + } hypercall; + +Except when running in compatibility mode with VMware hypervisors +userspace handling of hypercalls is discouraged. To implement +such functionality, use KVM_EXIT_IO (x86) or KVM_EXIT_MMIO +(all except s390). + 8. Other capabilities. ======================
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 7fcf185e337f..7fbb11682517 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1404,6 +1404,7 @@ struct kvm_arch { struct kvm_xen xen; #endif bool vmware_backdoor_enabled; + bool vmware_hypercall_enabled;
bool backwards_tsc_observed; bool boot_vcpu_runs_old_kvmclock; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d7071907d6a5..b676c54266e7 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4689,6 +4689,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_MEMORY_FAULT_INFO: case KVM_CAP_X86_GUEST_MODE: case KVM_CAP_X86_VMWARE_BACKDOOR: + case KVM_CAP_X86_VMWARE_HYPERCALL: r = 1; break; case KVM_CAP_PRE_FAULT_MEMORY: @@ -6784,6 +6785,13 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, } mutex_unlock(&kvm->lock); break; + case KVM_CAP_X86_VMWARE_HYPERCALL: + r = -EINVAL; + if (cap->args[0] & ~1) + break; + kvm->arch.vmware_hypercall_enabled = cap->args[0]; + r = 0; + break; default: r = -EINVAL; break; @@ -10127,6 +10135,28 @@ static int complete_hypercall_exit(struct kvm_vcpu *vcpu) return kvm_skip_emulated_instruction(vcpu); }
+static int kvm_vmware_hypercall(struct kvm_vcpu *vcpu) +{ + struct kvm_run *run = vcpu->run; + bool is_64_bit = is_64_bit_hypercall(vcpu); + u64 mask = is_64_bit ? U64_MAX : U32_MAX; + + vcpu->run->hypercall.flags = is_64_bit ? KVM_EXIT_HYPERCALL_LONG_MODE : 0; + run->hypercall.nr = kvm_rax_read(vcpu) & mask; + run->hypercall.args[0] = kvm_rbx_read(vcpu) & mask; + run->hypercall.args[1] = kvm_rcx_read(vcpu) & mask; + run->hypercall.args[2] = kvm_rdx_read(vcpu) & mask; + run->hypercall.args[3] = kvm_rsi_read(vcpu) & mask; + run->hypercall.args[4] = kvm_rdi_read(vcpu) & mask; + run->hypercall.args[5] = kvm_rbp_read(vcpu) & mask; + run->hypercall.ret = kvm_x86_call(get_cpl)(vcpu); + + run->exit_reason = KVM_EXIT_HYPERCALL; + vcpu->arch.complete_userspace_io = complete_hypercall_exit; + + return 0; +} + unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr, unsigned long a0, unsigned long a1, unsigned long a2, unsigned long a3, @@ -10225,6 +10255,9 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) int op_64_bit; int cpl;
+ if (vcpu->kvm->arch.vmware_hypercall_enabled) + return kvm_vmware_hypercall(vcpu); + if (kvm_xen_hypercall_enabled(vcpu->kvm)) return kvm_xen_hypercall(vcpu);
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index c7b5f1c2ee1c..4c2cc6ed29a0 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -934,6 +934,7 @@ struct kvm_enable_cap { #define KVM_CAP_X86_APIC_BUS_CYCLES_NS 237 #define KVM_CAP_X86_GUEST_MODE 238 #define KVM_CAP_X86_VMWARE_BACKDOOR 239 +#define KVM_CAP_X86_VMWARE_HYPERCALL 240
struct kvm_irq_routing_irqchip { __u32 irqchip;