Assert that KVM doesn't set a SPTE to a value that could trigger an EPT
Violation #VE on a non-MMIO SPTE, e.g. to help detect bugs even without
KVM_INTEL_PROVE_VE enabled, and to help debug actual #VE failures.
Note, this will run afoul of TDX support, which needs to reflect emulated
MMIO accesses into the guest as #VEs (which was the whole point of adding
EPT Violation #VE support in KVM). The obvious fix for that is to exempt
MMIO SPTEs, but that's annoyingly difficult now that is_mmio_spte() relies
on a per-VM value. However, resolving that conundrum is a future problem,
whereas getting KVM_INTEL_PROVE_VE healthy is a current problem.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <
20240518000430.
1118488-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
#ifdef CONFIG_X86_64
static void __set_spte(u64 *sptep, u64 spte)
{
+ KVM_MMU_WARN_ON(is_ept_ve_possible(spte));
WRITE_ONCE(*sptep, spte);
}
static void __update_clear_spte_fast(u64 *sptep, u64 spte)
{
+ KVM_MMU_WARN_ON(is_ept_ve_possible(spte));
WRITE_ONCE(*sptep, spte);
}
static u64 __update_clear_spte_slow(u64 *sptep, u64 spte)
{
+ KVM_MMU_WARN_ON(is_ept_ve_possible(spte));
return xchg(sptep, spte);
}
#ifndef KVM_X86_MMU_SPTE_H
#define KVM_X86_MMU_SPTE_H
+#include <asm/vmx.h>
+
#include "mmu.h"
#include "mmu_internal.h"
return !!(pte & SPTE_MMU_PRESENT_MASK);
}
+static inline bool is_ept_ve_possible(u64 spte)
+{
+ return (shadow_present_mask & VMX_EPT_SUPPRESS_VE_BIT) &&
+ !(spte & VMX_EPT_SUPPRESS_VE_BIT) &&
+ (spte & VMX_EPT_RWX_MASK) != VMX_EPT_MISCONFIG_WX_VALUE;
+}
+
/*
* Returns true if A/D bits are supported in hardware and are enabled by KVM.
* When enabled, KVM uses A/D bits for all non-nested MMUs. Because L1 can
static inline u64 kvm_tdp_mmu_write_spte_atomic(tdp_ptep_t sptep, u64 new_spte)
{
+ KVM_MMU_WARN_ON(is_ept_ve_possible(new_spte));
return xchg(rcu_dereference(sptep), new_spte);
}
static inline void __kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 new_spte)
{
+ KVM_MMU_WARN_ON(is_ept_ve_possible(new_spte));
WRITE_ONCE(*rcu_dereference(sptep), new_spte);
}