| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Mon, 26 Apr 2021 11:01:35 -0700
From: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Peter Zijlstra <peterz@...radead.org>,
Andy Lutomirski <luto@...nel.org>,
Dave Hansen <dave.hansen@...el.com>,
Dan Williams <dan.j.williams@...el.com>,
Tony Luck <tony.luck@...el.com>
Cc: Andi Kleen <ak@...ux.intel.com>,
Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
Raj Ashok <ashok.raj@...el.com>,
Sean Christopherson <seanjc@...gle.com>,
linux-kernel@...r.kernel.org,
Sean Christopherson <sean.j.christopherson@...el.com>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>
Subject: [RFC v2 08/32] x86/traps: Add #VE support for TDX guest
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
The TDX module injects #VE exception to the guest TD in cases of
disallowed instructions, disallowed MSR accesses and subset of CPUID
leaves. The TDX module guarantees that no #VE is injected on an EPT
violation on guest physical addresses that are memory. We can still
get #VE on MMIO mappings. This avoids any problems with the “system
call gap”.
Add basic infrastructure to handle #VE. If there is no handler for a
given #VE, since it is an unexpected event (fault case), treat it as
a general protection fault and handle it using
do_general_protection() call.
TDCALL[TDGETVEINFO] provides information about #VE such as exit reason.
The #VE cannot be nested before TDGETVEINFO is called, if there is any
reason for it to nest the TD would shut down. The TDX module guarantees
that no NMIs (or #MC or similar) can happen in this window. After
TDGETVEINFO the #VE handler can nest if needed, although we don’t expect
it to happen normally.
Co-developed-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Reviewed-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
---
arch/x86/include/asm/idtentry.h | 4 ++++
arch/x86/include/asm/tdx.h | 15 +++++++++++++
arch/x86/kernel/idt.c | 6 ++++++
arch/x86/kernel/tdx.c | 38 +++++++++++++++++++++++++++++++++
arch/x86/kernel/traps.c | 30 ++++++++++++++++++++++++++
5 files changed, 93 insertions(+)
diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 5eb3bdf36a41..41a0732d5f68 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -619,6 +619,10 @@ DECLARE_IDTENTRY_XENCB(X86_TRAP_OTHER, exc_xen_hypervisor_callback);
DECLARE_IDTENTRY_RAW(X86_TRAP_OTHER, exc_xen_unknown_trap);
#endif
+#ifdef CONFIG_INTEL_TDX_GUEST
+DECLARE_IDTENTRY(X86_TRAP_VE, exc_virtualization_exception);
+#endif
+
/* Device interrupts common/spurious */
DECLARE_IDTENTRY_IRQ(X86_TRAP_OTHER, common_interrupt);
#ifdef CONFIG_X86_LOCAL_APIC
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index c5a870cef0ae..1ca55d8e9963 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -11,6 +11,7 @@
#include <linux/types.h>
#define TDINFO 1
+#define TDGETVEINFO 3
struct tdcall_output {
u64 rcx;
@@ -29,6 +30,20 @@ struct tdvmcall_output {
u64 r15;
};
+struct ve_info {
+ u64 exit_reason;
+ u64 exit_qual;
+ u64 gla;
+ u64 gpa;
+ u32 instr_len;
+ u32 instr_info;
+};
+
+unsigned long tdg_get_ve_info(struct ve_info *ve);
+
+int tdg_handle_virtualization_exception(struct pt_regs *regs,
+ struct ve_info *ve);
+
/* Common API to check TDX support in decompression and common kernel code. */
bool is_tdx_guest(void);
diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index ee1a283f8e96..546b6b636c7d 100644
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -64,6 +64,9 @@ static const __initconst struct idt_data early_idts[] = {
*/
INTG(X86_TRAP_PF, asm_exc_page_fault),
#endif
+#ifdef CONFIG_INTEL_TDX_GUEST
+ INTG(X86_TRAP_VE, asm_exc_virtualization_exception),
+#endif
};
/*
@@ -87,6 +90,9 @@ static const __initconst struct idt_data def_idts[] = {
INTG(X86_TRAP_MF, asm_exc_coprocessor_error),
INTG(X86_TRAP_AC, asm_exc_alignment_check),
INTG(X86_TRAP_XF, asm_exc_simd_coprocessor_error),
+#ifdef CONFIG_INTEL_TDX_GUEST
+ INTG(X86_TRAP_VE, asm_exc_virtualization_exception),
+#endif
#ifdef CONFIG_X86_32
TSKG(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS),
diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c
index b63275db1db9..ccfcb07bfb2c 100644
--- a/arch/x86/kernel/tdx.c
+++ b/arch/x86/kernel/tdx.c
@@ -82,6 +82,44 @@ static void tdg_get_info(void)
td_info.attributes = out.rdx;
}
+unsigned long tdg_get_ve_info(struct ve_info *ve)
+{
+ u64 ret;
+ struct tdcall_output out = {0};
+
+ /*
+ * The #VE cannot be nested before TDGETVEINFO is called,
+ * if there is any reason for it to nest the TD would shut
+ * down. The TDX module guarantees that no NMIs (or #MC or
+ * similar) can happen in this window. After TDGETVEINFO
+ * the #VE handler can nest if needed, although we don’t
+ * expect it to happen normally.
+ */
+
+ ret = __tdcall(TDGETVEINFO, 0, 0, 0, 0, &out);
+
+ ve->exit_reason = out.rcx;
+ ve->exit_qual = out.rdx;
+ ve->gla = out.r8;
+ ve->gpa = out.r9;
+ ve->instr_len = out.r10 & UINT_MAX;
+ ve->instr_info = out.r10 >> 32;
+
+ return ret;
+}
+
+int tdg_handle_virtualization_exception(struct pt_regs *regs,
+ struct ve_info *ve)
+{
+ /*
+ * TODO: Add handler support for various #VE exit
+ * reasons. It will be added by other patches in
+ * the series.
+ */
+ pr_warn("Unexpected #VE: %lld\n", ve->exit_reason);
+ return -EFAULT;
+}
+
void __init tdx_early_init(void)
{
if (!cpuid_has_tdx_guest())
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 213d4aa8e337..64869aa88a5a 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -61,6 +61,7 @@
#include <asm/insn.h>
#include <asm/insn-eval.h>
#include <asm/vdso.h>
+#include <asm/tdx.h>
#ifdef CONFIG_X86_64
#include <asm/x86_init.h>
@@ -1140,6 +1141,35 @@ DEFINE_IDTENTRY(exc_device_not_available)
}
}
+#ifdef CONFIG_INTEL_TDX_GUEST
+DEFINE_IDTENTRY(exc_virtualization_exception)
+{
+ struct ve_info ve;
+ int ret;
+
+ RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
+
+ /*
+ * Consume #VE info before re-enabling interrupts. It will be
+ * re-enabled after executing the TDGETVEINFO TDCALL.
+ */
+ ret = tdg_get_ve_info(&ve);
+
+ cond_local_irq_enable(regs);
+
+ if (!ret)
+ ret = tdg_handle_virtualization_exception(regs, &ve);
+ /*
+ * If tdg_handle_virtualization_exception() could not process
+ * it successfully, treat it as #GP(0) and handle it.
+ */
+ if (ret)
+ do_general_protection(regs, 0);
+
+ cond_local_irq_disable(regs);
+}
+#endif
+
#ifdef CONFIG_X86_32
DEFINE_IDTENTRY_SW(iret_error)
{
--
2.25.1
Powered by blists - more mailing lists