[PATCH v3 10/12] KVM: x86/xen: Maintain valid mapping of Xen shared_info page
From: David Woodhouse <dwmw2@infradead.org>
Date: 2021-11-17 17:46:00
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-mips, linux-s390
Subsystem:
kernel virtual machine for x86 (kvm/x86), kvm x86 xen (kvm/xen), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, David Woodhouse, Paul Durrant, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: David Woodhouse <redacted> Use the newly reinstated gfn_to_pfn_cache to maintain a kernel mapping of the Xen shared_info page so that it can be accessed in atomic context. Signed-off-by: David Woodhouse <redacted> --- arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/xen.c | 25 ++++++++++++++----------- 2 files changed, 15 insertions(+), 12 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 6ac61f85e07b..4b2b4ecf3b46 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h@@ -1014,7 +1014,7 @@ struct msr_bitmap_range { struct kvm_xen { bool long_mode; u8 upcall_vector; - gfn_t shinfo_gfn; + struct gfn_to_pfn_cache shinfo_cache; }; enum kvm_irqchip_mode {
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index dff2bdf9507a..32a915a4fe20 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c@@ -23,16 +23,21 @@ DEFINE_STATIC_KEY_DEFERRED_FALSE(kvm_xen_enabled, HZ); static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn) { + struct gfn_to_pfn_cache *gpc = &kvm->arch.xen.shinfo_cache; gpa_t gpa = gfn_to_gpa(gfn); int wc_ofs, sec_hi_ofs; int ret = 0; int idx = srcu_read_lock(&kvm->srcu); - if (kvm_is_error_hva(gfn_to_hva(kvm, gfn))) { - ret = -EFAULT; + if (gfn == GPA_INVALID) { + kvm_gfn_to_pfn_cache_destroy(kvm, gpc); goto out; } - kvm->arch.xen.shinfo_gfn = gfn; + + ret = kvm_gfn_to_pfn_cache_init(kvm, gpc, NULL, false, true, gpa, + PAGE_SIZE, true); + if (ret) + goto out; /* Paranoia checks on the 32-bit struct layout */ BUILD_BUG_ON(offsetof(struct compat_shared_info, wc) != 0x900);
@@ -260,15 +265,9 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data) break; case KVM_XEN_ATTR_TYPE_SHARED_INFO: - if (data->u.shared_info.gfn == GPA_INVALID) { - kvm->arch.xen.shinfo_gfn = GPA_INVALID; - r = 0; - break; - } r = kvm_xen_shared_info_init(kvm, data->u.shared_info.gfn); break; - case KVM_XEN_ATTR_TYPE_UPCALL_VECTOR: if (data->u.vector && data->u.vector < 0x10) r = -EINVAL;
@@ -299,7 +298,10 @@ int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data) break; case KVM_XEN_ATTR_TYPE_SHARED_INFO: - data->u.shared_info.gfn = kvm->arch.xen.shinfo_gfn; + if (kvm->arch.xen.shinfo_cache.active) + data->u.shared_info.gfn = gpa_to_gfn(kvm->arch.xen.shinfo_cache.gpa); + else + data->u.shared_info.gfn = GPA_INVALID; r = 0; break;
@@ -661,11 +663,12 @@ int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc) void kvm_xen_init_vm(struct kvm *kvm) { - kvm->arch.xen.shinfo_gfn = GPA_INVALID; } void kvm_xen_destroy_vm(struct kvm *kvm) { + kvm_gfn_to_pfn_cache_destroy(kvm, &kvm->arch.xen.shinfo_cache); + if (kvm->arch.xen_hvm_config.msr) static_branch_slow_dec_deferred(&kvm_xen_enabled); }
--
2.31.1