Re: [PATCH V13 10/10] arm/arm64: KVM: add guest SEA support

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Hello Marc,


On 3/24/2017 8:03 AM, Marc Zyngier wrote:
On 21/03/17 22:47, Tyler Baicar wrote:
Currently external aborts are unsupported by the guest abort
handling. Add handling for SEAs so that the host kernel reports
SEAs which occur in the guest kernel.

Signed-off-by: Tyler Baicar <tbaicar@xxxxxxxxxxxxxx>
---
  arch/arm/include/asm/kvm_arm.h       | 10 +++++++++
  arch/arm/include/asm/system_misc.h   |  5 +++++
  arch/arm/kvm/mmu.c                   | 41 ++++++++++++++++++++++++++++++------
  arch/arm64/include/asm/kvm_arm.h     | 10 +++++++++
  arch/arm64/include/asm/system_misc.h |  2 ++
  arch/arm64/mm/fault.c                | 19 +++++++++++++++--
  drivers/acpi/apei/ghes.c             | 13 ++++++------
  include/acpi/ghes.h                  |  2 +-
  8 files changed, 86 insertions(+), 16 deletions(-)

diff --git a/arch/arm/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h
index a3f0b3d..ebf020b 100644
--- a/arch/arm/include/asm/kvm_arm.h
+++ b/arch/arm/include/asm/kvm_arm.h
@@ -187,6 +187,16 @@
  #define FSC_FAULT	(0x04)
  #define FSC_ACCESS	(0x08)
  #define FSC_PERM	(0x0c)
+#define FSC_SEA		(0x10)
+#define FSC_SEA_TTW0	(0x14)
+#define FSC_SEA_TTW1	(0x15)
+#define FSC_SEA_TTW2	(0x16)
+#define FSC_SEA_TTW3	(0x17)
+#define FSC_SECC	(0x18)
+#define FSC_SECC_TTW0	(0x1c)
+#define FSC_SECC_TTW1	(0x1d)
+#define FSC_SECC_TTW2	(0x1e)
+#define FSC_SECC_TTW3	(0x1f)
/* Hyp Prefetch Fault Address Register (HPFAR/HDFAR) */
  #define HPFAR_MASK	(~0xf)
diff --git a/arch/arm/include/asm/system_misc.h b/arch/arm/include/asm/system_misc.h
index a3d61ad..ea45d94 100644
--- a/arch/arm/include/asm/system_misc.h
+++ b/arch/arm/include/asm/system_misc.h
@@ -24,4 +24,9 @@
#endif /* !__ASSEMBLY__ */ +static inline int handle_guest_sea(unsigned long addr, unsigned int esr)
+{
+	return -1;
+}
+
Shouldn't this be in the #ifndef __ASSEMBLY__ block? The assembler is
definitely going to barf on that...
I will move this in the next patch set.
  #endif /* __ASM_ARM_SYSTEM_MISC_H */
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 962616f..105b6ab 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -29,6 +29,7 @@
  #include <asm/kvm_asm.h>
  #include <asm/kvm_emulate.h>
  #include <asm/virt.h>
+#include <asm/system_misc.h>
#include "trace.h" @@ -1406,6 +1407,24 @@ static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
  		kvm_set_pfn_accessed(pfn);
  }
+static bool is_abort_synchronous(unsigned long fault_status) {
+	switch (fault_status) {
+	case FSC_SEA:
+	case FSC_SEA_TTW0:
+	case FSC_SEA_TTW1:
+	case FSC_SEA_TTW2:
+	case FSC_SEA_TTW3:
+	case FSC_SECC:
+	case FSC_SECC_TTW0:
+	case FSC_SECC_TTW1:
+	case FSC_SECC_TTW2:
+	case FSC_SECC_TTW3:
+		return true;
+	default:
+		return false;
+	}
+}
+
  /**
   * kvm_handle_guest_abort - handles all 2nd stage aborts
   * @vcpu:	the VCPU pointer
@@ -1426,23 +1445,31 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
  	unsigned long hva;
  	bool is_iabt, write_fault, writable;
  	gfn_t gfn;
-	int ret, idx;
+	int ret, idx, sea_status = 1;
+
+	/* Check the stage-2 fault is trans. fault or write fault */
+	fault_status = kvm_vcpu_trap_get_fault_type(vcpu);
+
+	fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
+
+	/* The host kernel will handle the synchronous external abort. There
+	 * is no need to pass the error into the guest.
+	 */
+	if (is_abort_synchronous(fault_status))
+		sea_status = handle_guest_sea((unsigned long)fault_ipa,
+				    kvm_vcpu_get_hsr(vcpu));
is_iabt = kvm_vcpu_trap_is_iabt(vcpu);
-	if (unlikely(!is_iabt && kvm_vcpu_dabt_isextabt(vcpu))) {
+	if (unlikely(!is_iabt && kvm_vcpu_dabt_isextabt(vcpu)) && sea_status) {
  		kvm_inject_vabt(vcpu);
  		return 1;
  	}
- fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
-
  	trace_kvm_guest_fault(*vcpu_pc(vcpu), kvm_vcpu_get_hsr(vcpu),
  			      kvm_vcpu_get_hfar(vcpu), fault_ipa);
- /* Check the stage-2 fault is trans. fault or write fault */
-	fault_status = kvm_vcpu_trap_get_fault_type(vcpu);
  	if (fault_status != FSC_FAULT && fault_status != FSC_PERM &&
-	    fault_status != FSC_ACCESS) {
+	    fault_status != FSC_ACCESS && sea_status) {
  		kvm_err("Unsupported FSC: EC=%#x xFSC=%#lx ESR_EL2=%#lx\n",
  			kvm_vcpu_trap_get_class(vcpu),
  			(unsigned long)kvm_vcpu_trap_get_fault(vcpu),
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 6e99978..61d694c 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -204,6 +204,16 @@
  #define FSC_FAULT	ESR_ELx_FSC_FAULT
  #define FSC_ACCESS	ESR_ELx_FSC_ACCESS
  #define FSC_PERM	ESR_ELx_FSC_PERM
+#define FSC_SEA		ESR_ELx_FSC_EXTABT
+#define FSC_SEA_TTW0	(0x14)
+#define FSC_SEA_TTW1	(0x15)
+#define FSC_SEA_TTW2	(0x16)
+#define FSC_SEA_TTW3	(0x17)
+#define FSC_SECC	(0x18)
+#define FSC_SECC_TTW0	(0x1c)
+#define FSC_SECC_TTW1	(0x1d)
+#define FSC_SECC_TTW2	(0x1e)
+#define FSC_SECC_TTW3	(0x1f)
/* Hyp Prefetch Fault Address Register (HPFAR/HDFAR) */
  #define HPFAR_MASK	(~UL(0xf))
diff --git a/arch/arm64/include/asm/system_misc.h b/arch/arm64/include/asm/system_misc.h
index bc81243..5b2cecd 100644
--- a/arch/arm64/include/asm/system_misc.h
+++ b/arch/arm64/include/asm/system_misc.h
@@ -58,4 +58,6 @@ void hook_debug_fault_code(int nr, int (*fn)(unsigned long, unsigned int,
#endif /* __ASSEMBLY__ */ +int handle_guest_sea(unsigned long addr, unsigned int esr);
Same remark here.
Same here.

+
  #endif	/* __ASM_SYSTEM_MISC_H */
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index f7372ce..ee96307 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -497,6 +497,7 @@ static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
  static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
  {
  	struct siginfo info;
+	int ret = 0;
pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
  		 fault_name(esr), esr, addr);
@@ -508,7 +509,7 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
  	 */
  	if (IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
  		nmi_enter();
-		ghes_notify_sea();
+		ret = ghes_notify_sea();
  		nmi_exit();
  	}
@@ -521,7 +522,7 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
  		info.si_addr  = (void __user *)addr;
  	arm64_notify_die("", regs, &info, esr);
- return 0;
+	return ret;
  }
static const struct fault_info {
@@ -603,6 +604,20 @@ static const char *fault_name(unsigned int esr)
  }
/*
+ * Handle Synchronous External Aborts that occur in a guest kernel.
+ */
+int handle_guest_sea(unsigned long addr, unsigned int esr)
+{
+	int ret = -ENOENT;
+
+	if(IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
+		ret = ghes_notify_sea();
+	}
+
+	return ret;
+}
+
+/*
   * Dispatch a data abort to the relevant handler.
   */
  asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 230b095..81eabc6 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -810,17 +810,18 @@ static int ghes_notify_sci(struct notifier_block *this,
  #ifdef CONFIG_ACPI_APEI_SEA
  static LIST_HEAD(ghes_sea);
-void ghes_notify_sea(void)
+int ghes_notify_sea(void)
  {
  	struct ghes *ghes;
+	int ret = -ENOENT;
- /*
-	 * synchronize_rcu() will wait for nmi_exit(), so no need to
-	 * rcu_read_lock().
-	 */
+	rcu_read_lock();
  	list_for_each_entry_rcu(ghes, &ghes_sea, list) {
-		ghes_proc(ghes);
+		if(!ghes_proc(ghes))
+			ret = 0;
  	}
+	rcu_read_unlock();
+	return ret;
  }
static void ghes_sea_add(struct ghes *ghes)
diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h
index 18bc935..2a727dc 100644
--- a/include/acpi/ghes.h
+++ b/include/acpi/ghes.h
@@ -99,6 +99,6 @@ static inline void *acpi_hest_generic_data_payload(struct acpi_hest_generic_data
  		gdata + 1;
  }
-void ghes_notify_sea(void);
+int ghes_notify_sea(void);
#endif /* GHES_H */

Otherwise, the KVM changes look good to me. Assuming you fix the two
nits above:

Acked-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Thanks!
Tyler

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a Linux Foundation Collaborative Project.

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