| Message ID | 20241128004344.4072099-2-seanjc@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: x86: Prep KVM hypercall handling for TDX | expand |
On 11/28/2024 8:43 AM, Sean Christopherson wrote: > Use is_64_bit_hypercall() instead of is_64_bit_mode() to detect a 64-bit > hypercall when completing said hypercall. For guests with protected state, > e.g. SEV-ES and SEV-SNP, KVM must assume the hypercall was made in 64-bit > mode as the vCPU state needed to detect 64-bit mode is unavailable. > > Hacking the sev_smoke_test selftest to generate a KVM_HC_MAP_GPA_RANGE > hypercall via VMGEXIT trips the WARN: > > ------------[ cut here ]------------ > WARNING: CPU: 273 PID: 326626 at arch/x86/kvm/x86.h:180 complete_hypercall_exit+0x44/0xe0 [kvm] > Modules linked in: kvm_amd kvm ... [last unloaded: kvm] > CPU: 273 UID: 0 PID: 326626 Comm: sev_smoke_test Not tainted 6.12.0-smp--392e932fa0f3-feat #470 > Hardware name: Google Astoria/astoria, BIOS 0.20240617.0-0 06/17/2024 > RIP: 0010:complete_hypercall_exit+0x44/0xe0 [kvm] > Call Trace: > <TASK> > kvm_arch_vcpu_ioctl_run+0x2400/0x2720 [kvm] > kvm_vcpu_ioctl+0x54f/0x630 [kvm] > __se_sys_ioctl+0x6b/0xc0 > do_syscall_64+0x83/0x160 > entry_SYSCALL_64_after_hwframe+0x76/0x7e > </TASK> > ---[ end trace 0000000000000000 ]--- Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com> > Fixes: b5aead0064f3 ("KVM: x86: Assume a 64-bit hypercall for guests with protected state") > Cc: stable@vger.kernel.org > Cc: Tom Lendacky <thomas.lendacky@amd.com> > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/kvm/x86.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 2e713480933a..0b2fe4aa04a2 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -9976,7 +9976,7 @@ static int complete_hypercall_exit(struct kvm_vcpu *vcpu) > { > u64 ret = vcpu->run->hypercall.ret; > > - if (!is_64_bit_mode(vcpu)) > + if (!is_64_bit_hypercall(vcpu)) > ret = (u32)ret; > kvm_rax_write(vcpu, ret); > ++vcpu->stat.hypercalls;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 2e713480933a..0b2fe4aa04a2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -9976,7 +9976,7 @@ static int complete_hypercall_exit(struct kvm_vcpu *vcpu) { u64 ret = vcpu->run->hypercall.ret; - if (!is_64_bit_mode(vcpu)) + if (!is_64_bit_hypercall(vcpu)) ret = (u32)ret; kvm_rax_write(vcpu, ret); ++vcpu->stat.hypercalls;
Use is_64_bit_hypercall() instead of is_64_bit_mode() to detect a 64-bit hypercall when completing said hypercall. For guests with protected state, e.g. SEV-ES and SEV-SNP, KVM must assume the hypercall was made in 64-bit mode as the vCPU state needed to detect 64-bit mode is unavailable. Hacking the sev_smoke_test selftest to generate a KVM_HC_MAP_GPA_RANGE hypercall via VMGEXIT trips the WARN: ------------[ cut here ]------------ WARNING: CPU: 273 PID: 326626 at arch/x86/kvm/x86.h:180 complete_hypercall_exit+0x44/0xe0 [kvm] Modules linked in: kvm_amd kvm ... [last unloaded: kvm] CPU: 273 UID: 0 PID: 326626 Comm: sev_smoke_test Not tainted 6.12.0-smp--392e932fa0f3-feat #470 Hardware name: Google Astoria/astoria, BIOS 0.20240617.0-0 06/17/2024 RIP: 0010:complete_hypercall_exit+0x44/0xe0 [kvm] Call Trace: <TASK> kvm_arch_vcpu_ioctl_run+0x2400/0x2720 [kvm] kvm_vcpu_ioctl+0x54f/0x630 [kvm] __se_sys_ioctl+0x6b/0xc0 do_syscall_64+0x83/0x160 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK> ---[ end trace 0000000000000000 ]--- Fixes: b5aead0064f3 ("KVM: x86: Assume a 64-bit hypercall for guests with protected state") Cc: stable@vger.kernel.org Cc: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/x86.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)