The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d8971344f5739a9cc53f91f1f593ddd82265b93b Mon Sep 17 00:00:00 2001

From: Sean Christopherson seanjc@google.com Date: Wed, 21 Apr 2021 19:21:23 -0700 Subject: [PATCH] KVM: VMX: Truncate GPR value for DR and CR reads in !64-bit mode

Drop bits 63:32 when storing a DR/CR to a GPR when the vCPU is not in 64-bit mode. Per the SDM:

The operand size for these instructions is always 32 bits in non-64-bit modes, regardless of the operand-size attribute.

CR8 technically isn't affected as CR8 isn't accessible outside of 64-bit mode, but fix it up for consistency and to allow for future cleanup.

Fixes: 6aa8b732ca01 ("[PATCH] kvm: userspace interface") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20210422022128.3464144-5-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index edc23c77be32..64354b009fe0 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -5121,12 +5121,12 @@ static int handle_cr(struct kvm_vcpu *vcpu) case 3: WARN_ON_ONCE(enable_unrestricted_guest); val = kvm_read_cr3(vcpu); - kvm_register_write(vcpu, reg, val); + kvm_register_writel(vcpu, reg, val); trace_kvm_cr_read(cr, val); return kvm_skip_emulated_instruction(vcpu); case 8: val = kvm_get_cr8(vcpu); - kvm_register_write(vcpu, reg, val); + kvm_register_writel(vcpu, reg, val); trace_kvm_cr_read(cr, val); return kvm_skip_emulated_instruction(vcpu); } @@ -5199,7 +5199,7 @@ static int handle_dr(struct kvm_vcpu *vcpu) unsigned long val;

kvm_get_dr(vcpu, dr, &val); - kvm_register_write(vcpu, reg, val); + kvm_register_writel(vcpu, reg, val); err = 0; } else { err = kvm_set_dr(vcpu, dr, kvm_register_readl(vcpu, reg));