Commit beb9b301 authored by Sean Christopherson's avatar Sean Christopherson Committed by Wentao Guan
Browse files

KVM: x86: Play nice with protected guests in complete_hypercall_exit() 

stable inclusion
from stable-v6.6.68
commit 9b42d1e8e4fe9dc631162c04caa69b0d1860b0f0
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IBMDV1

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9b42d1e8e4fe9dc631162c04caa69b0d1860b0f0



--------------------------------

commit 9b42d1e8e4fe9dc631162c04caa69b0d1860b0f0 upstream.

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: b5aead00 ("KVM: x86: Assume a 64-bit hypercall for guests with protected state")
Cc: stable@vger.kernel.org
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: default avatarXiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: default avatarNikunj A Dadhania <nikunj@amd.com>
Reviewed-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: default avatarBinbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: default avatarKai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20241128004344.4072099-2-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarWentao Guan <guanwentao@uniontech.com>
parent 16a0cbac

arch/x86/kvm/x86.c

+1 −6
Original line number Diff line number Diff line
@@ -9933,13 +9933,8 @@ static int complete_hypercall_exit(struct kvm_vcpu *vcpu) 
{

	u64 ret = vcpu->run->hypercall.ret;



	/* Use is_64_bit_hypercall() instead of is_64_bit_mode() for Hygon CPUs */

	if (is_x86_vendor_hygon()) {

	if (!is_64_bit_hypercall(vcpu))

		ret = (u32)ret;

	} else if (!is_64_bit_mode(vcpu)) {

		ret = (u32)ret;

	}

	kvm_rax_write(vcpu, ret);

	++vcpu->stat.hypercalls;

	return kvm_skip_emulated_instruction(vcpu);