From: "Xin Li (Intel)" <xin@zytor.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
linux-doc@vger.kernel.org
Cc: pbonzini@redhat.com, seanjc@google.com, corbet@lwn.net,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
xin@zytor.com, luto@kernel.org, peterz@infradead.org,
andrew.cooper3@citrix.com, chao.gao@intel.com, hch@infradead.org
Subject: [PATCH v6 04/20] x86/cea: Export an API to get per CPU exception stacks for KVM to use
Date: Thu, 21 Aug 2025 15:36:13 -0700 [thread overview]
Message-ID: <20250821223630.984383-5-xin@zytor.com> (raw)
In-Reply-To: <20250821223630.984383-1-xin@zytor.com>
FRED introduced new fields in the host-state area of the VMCS for
stack levels 1->3 (HOST_IA32_FRED_RSP[123]), each respectively
corresponding to per CPU exception stacks for #DB, NMI and #DF.
KVM must populate these each time a vCPU is loaded onto a CPU.
Convert the __this_cpu_ist_{top,bottom}_va() macros into real
functions and export __this_cpu_ist_top_va().
Suggested-by: Christoph Hellwig <hch@infradead.org>
Suggested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
---
Change in v5:
* Export accessor instead of data (Christoph Hellwig).
* Add TB from Xuelian Guo.
Change in v4:
* Rewrite the change log and add comments to the export (Dave Hansen).
---
arch/x86/coco/sev/sev-nmi.c | 4 ++--
arch/x86/coco/sev/vc-handle.c | 2 +-
arch/x86/include/asm/cpu_entry_area.h | 17 ++++-------------
arch/x86/kernel/cpu/common.c | 10 +++++-----
arch/x86/kernel/fred.c | 6 +++---
arch/x86/kernel/traps.c | 2 +-
arch/x86/mm/cpu_entry_area.c | 21 +++++++++++++++++++++
arch/x86/mm/fault.c | 2 +-
8 files changed, 38 insertions(+), 26 deletions(-)
diff --git a/arch/x86/coco/sev/sev-nmi.c b/arch/x86/coco/sev/sev-nmi.c
index d8dfaddfb367..73e34ad7a1a9 100644
--- a/arch/x86/coco/sev/sev-nmi.c
+++ b/arch/x86/coco/sev/sev-nmi.c
@@ -30,7 +30,7 @@ static __always_inline bool on_vc_stack(struct pt_regs *regs)
if (ip_within_syscall_gap(regs))
return false;
- return ((sp >= __this_cpu_ist_bottom_va(VC)) && (sp < __this_cpu_ist_top_va(VC)));
+ return ((sp >= __this_cpu_ist_bottom_va(ESTACK_VC)) && (sp < __this_cpu_ist_top_va(ESTACK_VC)));
}
/*
@@ -82,7 +82,7 @@ void noinstr __sev_es_ist_exit(void)
/* Read IST entry */
ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]);
- if (WARN_ON(ist == __this_cpu_ist_top_va(VC)))
+ if (WARN_ON(ist == __this_cpu_ist_top_va(ESTACK_VC)))
return;
/* Read back old IST entry and write it to the TSS */
diff --git a/arch/x86/coco/sev/vc-handle.c b/arch/x86/coco/sev/vc-handle.c
index c3b4acbde0d8..88b6bc518a5a 100644
--- a/arch/x86/coco/sev/vc-handle.c
+++ b/arch/x86/coco/sev/vc-handle.c
@@ -859,7 +859,7 @@ static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt,
static __always_inline bool is_vc2_stack(unsigned long sp)
{
- return (sp >= __this_cpu_ist_bottom_va(VC2) && sp < __this_cpu_ist_top_va(VC2));
+ return (sp >= __this_cpu_ist_bottom_va(ESTACK_VC2) && sp < __this_cpu_ist_top_va(ESTACK_VC2));
}
static __always_inline bool vc_from_invalid_context(struct pt_regs *regs)
diff --git a/arch/x86/include/asm/cpu_entry_area.h b/arch/x86/include/asm/cpu_entry_area.h
index 462fc34f1317..8e17f0ca74e6 100644
--- a/arch/x86/include/asm/cpu_entry_area.h
+++ b/arch/x86/include/asm/cpu_entry_area.h
@@ -46,7 +46,7 @@ struct cea_exception_stacks {
* The exception stack ordering in [cea_]exception_stacks
*/
enum exception_stack_ordering {
- ESTACK_DF,
+ ESTACK_DF = 0,
ESTACK_NMI,
ESTACK_DB,
ESTACK_MCE,
@@ -58,18 +58,15 @@ enum exception_stack_ordering {
#define CEA_ESTACK_SIZE(st) \
sizeof(((struct cea_exception_stacks *)0)->st## _stack)
-#define CEA_ESTACK_BOT(ceastp, st) \
- ((unsigned long)&(ceastp)->st## _stack)
-
-#define CEA_ESTACK_TOP(ceastp, st) \
- (CEA_ESTACK_BOT(ceastp, st) + CEA_ESTACK_SIZE(st))
-
#define CEA_ESTACK_OFFS(st) \
offsetof(struct cea_exception_stacks, st## _stack)
#define CEA_ESTACK_PAGES \
(sizeof(struct cea_exception_stacks) / PAGE_SIZE)
+extern unsigned long __this_cpu_ist_top_va(enum exception_stack_ordering stack);
+extern unsigned long __this_cpu_ist_bottom_va(enum exception_stack_ordering stack);
+
#endif
#ifdef CONFIG_X86_32
@@ -144,10 +141,4 @@ static __always_inline struct entry_stack *cpu_entry_stack(int cpu)
return &get_cpu_entry_area(cpu)->entry_stack_page.stack;
}
-#define __this_cpu_ist_top_va(name) \
- CEA_ESTACK_TOP(__this_cpu_read(cea_exception_stacks), name)
-
-#define __this_cpu_ist_bottom_va(name) \
- CEA_ESTACK_BOT(__this_cpu_read(cea_exception_stacks), name)
-
#endif
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 34a054181c4d..cb14919f92da 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2307,12 +2307,12 @@ static inline void setup_getcpu(int cpu)
static inline void tss_setup_ist(struct tss_struct *tss)
{
/* Set up the per-CPU TSS IST stacks */
- tss->x86_tss.ist[IST_INDEX_DF] = __this_cpu_ist_top_va(DF);
- tss->x86_tss.ist[IST_INDEX_NMI] = __this_cpu_ist_top_va(NMI);
- tss->x86_tss.ist[IST_INDEX_DB] = __this_cpu_ist_top_va(DB);
- tss->x86_tss.ist[IST_INDEX_MCE] = __this_cpu_ist_top_va(MCE);
+ tss->x86_tss.ist[IST_INDEX_DF] = __this_cpu_ist_top_va(ESTACK_DF);
+ tss->x86_tss.ist[IST_INDEX_NMI] = __this_cpu_ist_top_va(ESTACK_NMI);
+ tss->x86_tss.ist[IST_INDEX_DB] = __this_cpu_ist_top_va(ESTACK_DB);
+ tss->x86_tss.ist[IST_INDEX_MCE] = __this_cpu_ist_top_va(ESTACK_MCE);
/* Only mapped when SEV-ES is active */
- tss->x86_tss.ist[IST_INDEX_VC] = __this_cpu_ist_top_va(VC);
+ tss->x86_tss.ist[IST_INDEX_VC] = __this_cpu_ist_top_va(ESTACK_VC);
}
#else /* CONFIG_X86_64 */
static inline void tss_setup_ist(struct tss_struct *tss) { }
diff --git a/arch/x86/kernel/fred.c b/arch/x86/kernel/fred.c
index 816187da3a47..06d944a3d051 100644
--- a/arch/x86/kernel/fred.c
+++ b/arch/x86/kernel/fred.c
@@ -87,7 +87,7 @@ void cpu_init_fred_rsps(void)
FRED_STKLVL(X86_TRAP_DF, FRED_DF_STACK_LEVEL));
/* The FRED equivalents to IST stacks... */
- wrmsrq(MSR_IA32_FRED_RSP1, __this_cpu_ist_top_va(DB));
- wrmsrq(MSR_IA32_FRED_RSP2, __this_cpu_ist_top_va(NMI));
- wrmsrq(MSR_IA32_FRED_RSP3, __this_cpu_ist_top_va(DF));
+ wrmsrq(MSR_IA32_FRED_RSP1, __this_cpu_ist_top_va(ESTACK_DB));
+ wrmsrq(MSR_IA32_FRED_RSP2, __this_cpu_ist_top_va(ESTACK_NMI));
+ wrmsrq(MSR_IA32_FRED_RSP3, __this_cpu_ist_top_va(ESTACK_DF));
}
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 36354b470590..5c9c5ebf5e73 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -954,7 +954,7 @@ asmlinkage __visible noinstr struct pt_regs *vc_switch_off_ist(struct pt_regs *r
if (!get_stack_info_noinstr(stack, current, &info) || info.type == STACK_TYPE_ENTRY ||
info.type > STACK_TYPE_EXCEPTION_LAST)
- sp = __this_cpu_ist_top_va(VC2);
+ sp = __this_cpu_ist_top_va(ESTACK_VC2);
sync:
/*
diff --git a/arch/x86/mm/cpu_entry_area.c b/arch/x86/mm/cpu_entry_area.c
index 575f863f3c75..eedaf103c8ad 100644
--- a/arch/x86/mm/cpu_entry_area.c
+++ b/arch/x86/mm/cpu_entry_area.c
@@ -18,6 +18,27 @@ static DEFINE_PER_CPU_PAGE_ALIGNED(struct entry_stack_page, entry_stack_storage)
static DEFINE_PER_CPU_PAGE_ALIGNED(struct exception_stacks, exception_stacks);
DEFINE_PER_CPU(struct cea_exception_stacks*, cea_exception_stacks);
+/*
+ * FRED introduced new fields in the host-state area of the VMCS for
+ * stack levels 1->3 (HOST_IA32_FRED_RSP[123]), each respectively
+ * corresponding to per CPU stacks for #DB, NMI and #DF. KVM must
+ * populate these each time a vCPU is loaded onto a CPU.
+ *
+ * Called from entry code, so must be noinstr.
+ */
+noinstr unsigned long __this_cpu_ist_top_va(enum exception_stack_ordering stack)
+{
+ unsigned long base = (unsigned long)&(__this_cpu_read(cea_exception_stacks)->DF_stack);
+ return base + EXCEPTION_STKSZ + stack * (EXCEPTION_STKSZ + PAGE_SIZE);
+}
+EXPORT_SYMBOL(__this_cpu_ist_top_va);
+
+noinstr unsigned long __this_cpu_ist_bottom_va(enum exception_stack_ordering stack)
+{
+ unsigned long base = (unsigned long)&(__this_cpu_read(cea_exception_stacks)->DF_stack);
+ return base + stack * (EXCEPTION_STKSZ + PAGE_SIZE);
+}
+
static DEFINE_PER_CPU_READ_MOSTLY(unsigned long, _cea_offset);
static __always_inline unsigned int cea_offset(unsigned int cpu)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 998bd807fc7b..1804eb86cc14 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -671,7 +671,7 @@ page_fault_oops(struct pt_regs *regs, unsigned long error_code,
* and then double-fault, though, because we're likely to
* break the console driver and lose most of the stack dump.
*/
- call_on_stack(__this_cpu_ist_top_va(DF) - sizeof(void*),
+ call_on_stack(__this_cpu_ist_top_va(ESTACK_DF) - sizeof(void*),
handle_stack_overflow,
ASM_CALL_ARG3,
, [arg1] "r" (regs), [arg2] "r" (address), [arg3] "r" (&info));
--
2.50.1
next prev parent reply other threads:[~2025-08-21 22:37 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-21 22:36 [PATCH v6 00/20] Enable FRED with KVM VMX Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 01/20] KVM: VMX: Add support for the secondary VM exit controls Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 02/20] KVM: VMX: Initialize VM entry/exit FRED controls in vmcs_config Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 03/20] KVM: VMX: Disable FRED if FRED consistency checks fail Xin Li (Intel)
2025-08-21 22:36 ` Xin Li (Intel) [this message]
2025-08-27 17:33 ` [PATCH v6 04/20] x86/cea: Export an API to get per CPU exception stacks for KVM to use Dave Hansen
2025-08-27 22:18 ` Xin Li
2025-08-21 22:36 ` [PATCH v6 05/20] KVM: VMX: Initialize VMCS FRED fields Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 06/20] KVM: VMX: Set FRED MSR intercepts Xin Li (Intel)
2025-08-25 2:51 ` Xin Li
2025-08-26 18:11 ` Sean Christopherson
2025-08-26 21:59 ` Xin Li
2025-08-26 22:17 ` Sean Christopherson
2025-08-27 22:24 ` Xin Li
2025-08-27 22:43 ` Xin Li
2025-08-28 23:32 ` Sean Christopherson
2025-08-26 18:50 ` Andrew Cooper
2025-08-26 22:03 ` Xin Li
2025-08-26 22:20 ` Andrew Cooper
2025-08-21 22:36 ` [PATCH v6 07/20] KVM: VMX: Save/restore guest FRED RSP0 Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 08/20] KVM: VMX: Add support for FRED context save/restore Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 09/20] KVM: x86: Add a helper to detect if FRED is enabled for a vCPU Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 10/20] KVM: VMX: Virtualize FRED event_data Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 11/20] KVM: VMX: Virtualize FRED nested exception tracking Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 12/20] KVM: x86: Save/restore the nested flag of an exception Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 13/20] KVM: x86: Mark CR4.FRED as not reserved Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 14/20] KVM: VMX: Dump FRED context in dump_vmcs() Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 15/20] KVM: x86: Advertise support for FRED Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 16/20] KVM: nVMX: Add support for the secondary VM exit controls Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 17/20] KVM: nVMX: Add FRED VMCS fields to nested VMX context handling Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 18/20] KVM: nVMX: Add FRED-related VMCS field checks Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 19/20] KVM: nVMX: Add prerequisites to SHADOW_FIELD_R[OW] macros Xin Li (Intel)
2025-08-21 22:36 ` [PATCH v6 20/20] KVM: nVMX: Allow VMX FRED controls Xin Li (Intel)
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