[PATCH 4.14 124/156] x86/xen: Support early interrupts in xen pv guests

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

--

From: Juergen Gross 


[ Upstream commit 42b3a4cb5609de757f5445fcad18945ba9239a07 ]

Add early interrupt handlers activated by idt_setup_early_handler() to
the handlers supported by Xen pv guests. This will allow for early
WARN() calls not crashing the guest.

Suggested-by: Andy Lutomirski 
Signed-off-by: Juergen Gross 
Signed-off-by: Thomas Gleixner 
Cc: xen-de...@lists.xenproject.org
Cc: boris.ostrov...@oracle.com
Link: https://lkml.kernel.org/r/20171124084221.30172-1-jgr...@suse.com
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman 
---
 arch/x86/include/asm/segment.h |   12 
 arch/x86/mm/extable.c  |4 +++-
 arch/x86/xen/enlighten_pv.c|   37 -
 arch/x86/xen/xen-asm_64.S  |   14 ++
 4 files changed, 53 insertions(+), 14 deletions(-)

--- a/arch/x86/include/asm/segment.h
+++ b/arch/x86/include/asm/segment.h
@@ -236,11 +236,23 @@
  */
 #define EARLY_IDT_HANDLER_SIZE 9
 
+/*
+ * xen_early_idt_handler_array is for Xen pv guests: for each entry in
+ * early_idt_handler_array it contains a prequel in the form of
+ * pop %rcx; pop %r11; jmp early_idt_handler_array[i]; summing up to
+ * max 8 bytes.
+ */
+#define XEN_EARLY_IDT_HANDLER_SIZE 8
+
 #ifndef __ASSEMBLY__
 
 extern const char 
early_idt_handler_array[NUM_EXCEPTION_VECTORS][EARLY_IDT_HANDLER_SIZE];
 extern void early_ignore_irq(void);
 
+#if defined(CONFIG_X86_64) && defined(CONFIG_XEN_PV)
+extern const char 
xen_early_idt_handler_array[NUM_EXCEPTION_VECTORS][XEN_EARLY_IDT_HANDLER_SIZE];
+#endif
+
 /*
  * Load a segment. Fall back on loading the zero segment if something goes
  * wrong.  This variant assumes that loading zero fully clears the segment.
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -1,6 +1,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 #include 
@@ -212,8 +213,9 @@ void __init early_fixup_exception(struct
 * Old CPUs leave the high bits of CS on the stack
 * undefined.  I'm not sure which CPUs do this, but at least
 * the 486 DX works this way.
+* Xen pv domains are not using the default __KERNEL_CS.
 */
-   if (regs->cs != __KERNEL_CS)
+   if (!xen_pv_domain() && regs->cs != __KERNEL_CS)
goto fail;
 
/*
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -622,7 +622,7 @@ static struct trap_array_entry trap_arra
{ simd_coprocessor_error,  xen_simd_coprocessor_error,  false },
 };
 
-static bool get_trap_addr(void **addr, unsigned int ist)
+static bool __ref get_trap_addr(void **addr, unsigned int ist)
 {
unsigned int nr;
bool ist_okay = false;
@@ -644,6 +644,14 @@ static bool get_trap_addr(void **addr, u
}
}
 
+   if (nr == ARRAY_SIZE(trap_array) &&
+   *addr >= (void *)early_idt_handler_array[0] &&
+   *addr < (void *)early_idt_handler_array[NUM_EXCEPTION_VECTORS]) {
+   nr = (*addr - (void *)early_idt_handler_array[0]) /
+EARLY_IDT_HANDLER_SIZE;
+   *addr = (void *)xen_early_idt_handler_array[nr];
+   }
+
if (WARN_ON(ist != 0 && !ist_okay))
return false;
 
@@ -1261,6 +1269,21 @@ asmlinkage __visible void __init xen_sta
xen_setup_gdt(0);
 
xen_init_irq_ops();
+
+   /* Let's presume PV guests always boot on vCPU with id 0. */
+   per_cpu(xen_vcpu_id, 0) = 0;
+
+   /*
+* Setup xen_vcpu early because idt_setup_early_handler needs it for
+* local_irq_disable(), irqs_disabled().
+*
+* Don't do the full vcpu_info placement stuff until we have
+* the cpu_possible_mask and a non-dummy shared_info.
+*/
+   xen_vcpu_info_reset(0);
+
+   idt_setup_early_handler();
+
xen_init_capabilities();
 
 #ifdef CONFIG_X86_LOCAL_APIC
@@ -1294,18 +1317,6 @@ asmlinkage __visible void __init xen_sta
 */
acpi_numa = -1;
 #endif
-   /* Let's presume PV guests always boot on vCPU with id 0. */
-   per_cpu(xen_vcpu_id, 0) = 0;
-
-   /*
-* Setup xen_vcpu early because start_kernel needs it for
-* local_irq_disable(), irqs_disabled().
-*
-* Don't do the full vcpu_info placement stuff until we have
-* the cpu_possible_mask and a non-dummy shared_info.
-*/
-   xen_vcpu_info_reset(0);
-
WARN_ON(xen_cpuhp_setup(xen_cpu_up_prepare_pv, xen_cpu_dead_pv));
 
local_irq_disable();
--- a/arch/x86/xen/xen-asm_64.S
+++ b/arch/x86/xen/xen-asm_64.S
@@ -15,6 +15,7 @@
 
 #include 
 
+#include 
 #include 
 
 .macro xen_pv_trap name
@@ -54,6 +55,19 @@ xen_pv_trap entry_INT80_compat
 #endif
 xen_pv_trap hypervisor_callback
 
+   

[PATCH 4.14 124/156] x86/xen: Support early interrupts in xen pv guests

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

--

From: Juergen Gross 


[ Upstream commit 42b3a4cb5609de757f5445fcad18945ba9239a07 ]

Add early interrupt handlers activated by idt_setup_early_handler() to
the handlers supported by Xen pv guests. This will allow for early
WARN() calls not crashing the guest.

Suggested-by: Andy Lutomirski 
Signed-off-by: Juergen Gross 
Signed-off-by: Thomas Gleixner 
Cc: xen-de...@lists.xenproject.org
Cc: boris.ostrov...@oracle.com
Link: https://lkml.kernel.org/r/20171124084221.30172-1-jgr...@suse.com
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman 
---
 arch/x86/include/asm/segment.h |   12 
 arch/x86/mm/extable.c  |4 +++-
 arch/x86/xen/enlighten_pv.c|   37 -
 arch/x86/xen/xen-asm_64.S  |   14 ++
 4 files changed, 53 insertions(+), 14 deletions(-)

--- a/arch/x86/include/asm/segment.h
+++ b/arch/x86/include/asm/segment.h
@@ -236,11 +236,23 @@
  */
 #define EARLY_IDT_HANDLER_SIZE 9
 
+/*
+ * xen_early_idt_handler_array is for Xen pv guests: for each entry in
+ * early_idt_handler_array it contains a prequel in the form of
+ * pop %rcx; pop %r11; jmp early_idt_handler_array[i]; summing up to
+ * max 8 bytes.
+ */
+#define XEN_EARLY_IDT_HANDLER_SIZE 8
+
 #ifndef __ASSEMBLY__
 
 extern const char 
early_idt_handler_array[NUM_EXCEPTION_VECTORS][EARLY_IDT_HANDLER_SIZE];
 extern void early_ignore_irq(void);
 
+#if defined(CONFIG_X86_64) && defined(CONFIG_XEN_PV)
+extern const char 
xen_early_idt_handler_array[NUM_EXCEPTION_VECTORS][XEN_EARLY_IDT_HANDLER_SIZE];
+#endif
+
 /*
  * Load a segment. Fall back on loading the zero segment if something goes
  * wrong.  This variant assumes that loading zero fully clears the segment.
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -1,6 +1,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 #include 
@@ -212,8 +213,9 @@ void __init early_fixup_exception(struct
 * Old CPUs leave the high bits of CS on the stack
 * undefined.  I'm not sure which CPUs do this, but at least
 * the 486 DX works this way.
+* Xen pv domains are not using the default __KERNEL_CS.
 */
-   if (regs->cs != __KERNEL_CS)
+   if (!xen_pv_domain() && regs->cs != __KERNEL_CS)
goto fail;
 
/*
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -622,7 +622,7 @@ static struct trap_array_entry trap_arra
{ simd_coprocessor_error,  xen_simd_coprocessor_error,  false },
 };
 
-static bool get_trap_addr(void **addr, unsigned int ist)
+static bool __ref get_trap_addr(void **addr, unsigned int ist)
 {
unsigned int nr;
bool ist_okay = false;
@@ -644,6 +644,14 @@ static bool get_trap_addr(void **addr, u
}
}
 
+   if (nr == ARRAY_SIZE(trap_array) &&
+   *addr >= (void *)early_idt_handler_array[0] &&
+   *addr < (void *)early_idt_handler_array[NUM_EXCEPTION_VECTORS]) {
+   nr = (*addr - (void *)early_idt_handler_array[0]) /
+EARLY_IDT_HANDLER_SIZE;
+   *addr = (void *)xen_early_idt_handler_array[nr];
+   }
+
if (WARN_ON(ist != 0 && !ist_okay))
return false;
 
@@ -1261,6 +1269,21 @@ asmlinkage __visible void __init xen_sta
xen_setup_gdt(0);
 
xen_init_irq_ops();
+
+   /* Let's presume PV guests always boot on vCPU with id 0. */
+   per_cpu(xen_vcpu_id, 0) = 0;
+
+   /*
+* Setup xen_vcpu early because idt_setup_early_handler needs it for
+* local_irq_disable(), irqs_disabled().
+*
+* Don't do the full vcpu_info placement stuff until we have
+* the cpu_possible_mask and a non-dummy shared_info.
+*/
+   xen_vcpu_info_reset(0);
+
+   idt_setup_early_handler();
+
xen_init_capabilities();
 
 #ifdef CONFIG_X86_LOCAL_APIC
@@ -1294,18 +1317,6 @@ asmlinkage __visible void __init xen_sta
 */
acpi_numa = -1;
 #endif
-   /* Let's presume PV guests always boot on vCPU with id 0. */
-   per_cpu(xen_vcpu_id, 0) = 0;
-
-   /*
-* Setup xen_vcpu early because start_kernel needs it for
-* local_irq_disable(), irqs_disabled().
-*
-* Don't do the full vcpu_info placement stuff until we have
-* the cpu_possible_mask and a non-dummy shared_info.
-*/
-   xen_vcpu_info_reset(0);
-
WARN_ON(xen_cpuhp_setup(xen_cpu_up_prepare_pv, xen_cpu_dead_pv));
 
local_irq_disable();
--- a/arch/x86/xen/xen-asm_64.S
+++ b/arch/x86/xen/xen-asm_64.S
@@ -15,6 +15,7 @@
 
 #include 
 
+#include 
 #include 
 
 .macro xen_pv_trap name
@@ -54,6 +55,19 @@ xen_pv_trap entry_INT80_compat
 #endif
 xen_pv_trap hypervisor_callback
 
+   __INIT
+ENTRY(xen_early_idt_handler_array)
+   i = 0
+   .rept NUM_EXCEPTION_VECTORS
+   pop %rcx
+   pop