[PATCH 2/3] kvm/vmx: limit guest_phys_bits to 48 without 5-level ept

From: Gerd Hoffmann <kraxel@redhat.com>
To: kvm@vger.kernel.org
Cc: Gerd Hoffmann <kraxel@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
	"H. Peter Anvin" <hpa@zytor.com>,
	linux-kernel@vger.kernel.org (open list:X86 ARCHITECTURE (32-BIT
	AND 64-BIT))
Subject: [PATCH 2/3] kvm/vmx: limit guest_phys_bits to 48 without 5-level ept
Date: Fri,  1 Mar 2024 11:14:08 +0100	[thread overview]
Message-ID: <20240301101410.356007-3-kraxel@redhat.com> (raw)
In-Reply-To: <20240301101410.356007-1-kraxel@redhat.com>

If EPT has no support for 5-level paging the guest physical address
space is limited to 48 bits.  Adjust kvm_caps.guest_phys_bits
accordingly.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 arch/x86/kvm/vmx/vmx.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 1111d9d08903..8bd644a5022d 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7899,6 +7899,11 @@ static __init void vmx_set_cpu_caps(void)
 
 	if (cpu_has_vmx_waitpkg())
 		kvm_cpu_cap_check_and_set(X86_FEATURE_WAITPKG);
+
+	if (enable_ept &&
+	    !cpu_has_vmx_ept_5levels() &&
+	    kvm_caps.guest_phys_bits > 48)
+		kvm_caps.guest_phys_bits = 48;
 }
 
 static void vmx_request_immediate_exit(struct kvm_vcpu *vcpu)
-- 
2.44.0

