diff options
author | Sean Christopherson <seanjc@google.com> | 2022-08-04 01:49:56 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-08-17 16:13:45 +0300 |
commit | 16c6a078c2bb4986a2298f11478ef9ea62f8961e (patch) | |
tree | 26cd24719d9bffa89203f0e6251971c500f783a3 /arch/x86 | |
parent | 7f04ed0d95db3550a639c987d3177354b99cee1d (diff) | |
download | linux-16c6a078c2bb4986a2298f11478ef9ea62f8961e.tar.xz |
KVM: x86/mmu: Fully re-evaluate MMIO caching when SPTE masks change
commit c3e0c8c2e8b17bae30d5978bc2decdd4098f0f99 upstream.
Fully re-evaluate whether or not MMIO caching can be enabled when SPTE
masks change; simply clearing enable_mmio_caching when a configuration
isn't compatible with caching fails to handle the scenario where the
masks are updated, e.g. by VMX for EPT or by SVM to account for the C-bit
location, and toggle compatibility from false=>true.
Snapshot the original module param so that re-evaluating MMIO caching
preserves userspace's desire to allow caching. Use a snapshot approach
so that enable_mmio_caching still reflects KVM's actual behavior.
Fixes: 8b9e74bfbf8c ("KVM: x86/mmu: Use enable_mmio_caching to track if MMIO caching is enabled")
Reported-by: Michael Roth <michael.roth@amd.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: stable@vger.kernel.org
Tested-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Message-Id: <20220803224957.1285926-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86')
-rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 4 | ||||
-rw-r--r-- | arch/x86/kvm/mmu/spte.c | 19 | ||||
-rw-r--r-- | arch/x86/kvm/mmu/spte.h | 1 |
3 files changed, 24 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index b3a1748360d4..356226c7ebbd 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -6274,11 +6274,15 @@ static int set_nx_huge_pages(const char *val, const struct kernel_param *kp) /* * nx_huge_pages needs to be resolved to true/false when kvm.ko is loaded, as * its default value of -1 is technically undefined behavior for a boolean. + * Forward the module init call to SPTE code so that it too can handle module + * params that need to be resolved/snapshot. */ void __init kvm_mmu_x86_module_init(void) { if (nx_huge_pages == -1) __set_nx_huge_pages(get_nx_auto_mode()); + + kvm_mmu_spte_module_init(); } /* diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c index dfdc727a12ad..ba1be0159095 100644 --- a/arch/x86/kvm/mmu/spte.c +++ b/arch/x86/kvm/mmu/spte.c @@ -20,6 +20,7 @@ #include <asm/vmx.h> bool __read_mostly enable_mmio_caching = true; +static bool __ro_after_init allow_mmio_caching; module_param_named(mmio_caching, enable_mmio_caching, bool, 0444); EXPORT_SYMBOL_GPL(enable_mmio_caching); @@ -43,6 +44,18 @@ u64 __read_mostly shadow_nonpresent_or_rsvd_lower_gfn_mask; u8 __read_mostly shadow_phys_bits; +void __init kvm_mmu_spte_module_init(void) +{ + /* + * Snapshot userspace's desire to allow MMIO caching. Whether or not + * KVM can actually enable MMIO caching depends on vendor-specific + * hardware capabilities and other module params that can't be resolved + * until the vendor module is loaded, i.e. enable_mmio_caching can and + * will change when the vendor module is (re)loaded. + */ + allow_mmio_caching = enable_mmio_caching; +} + static u64 generation_mmio_spte_mask(u64 gen) { u64 mask; @@ -338,6 +351,12 @@ void kvm_mmu_set_mmio_spte_mask(u64 mmio_value, u64 mmio_mask, u64 access_mask) BUG_ON((u64)(unsigned)access_mask != access_mask); WARN_ON(mmio_value & shadow_nonpresent_or_rsvd_lower_gfn_mask); + /* + * Reset to the original module param value to honor userspace's desire + * to (dis)allow MMIO caching. Update the param itself so that + * userspace can see whether or not KVM is actually using MMIO caching. + */ + enable_mmio_caching = allow_mmio_caching; if (!enable_mmio_caching) mmio_value = 0; diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h index 7f0af695fd38..f80dbb628df5 100644 --- a/arch/x86/kvm/mmu/spte.h +++ b/arch/x86/kvm/mmu/spte.h @@ -444,6 +444,7 @@ static inline u64 restore_acc_track_spte(u64 spte) u64 kvm_mmu_changed_pte_notifier_make_spte(u64 old_spte, kvm_pfn_t new_pfn); +void __init kvm_mmu_spte_module_init(void); void kvm_mmu_reset_all_pte_masks(void); #endif |