[kvm-unit-tests PATCH v2 0/9] arm64: support EL2

[kvm-unit-tests PATCH v2 0/9] arm64: support EL2

[Joey Gouly]

Hi all,

This series is for adding support to running the kvm-unit-tests at EL2. These
have been tested with Marc Zyngier's Linux kvm-arm64/nv-next branch [1] and
kvmtool branch arm64/nv-6.13 [2]

The goal is to later extend and add new tests for Nested Virtualisation,
however they should also work with bare metal as well.

Changes since v1[3]:
	- Authorship fixed on 2 patches
	- Tested and fixed EFI support
	- Recactored assembly and added init_el macro
	- Clear trap registers, trying to avoid relying on default register
	  state
	- Cleaned up PMU changes

The debug tests fail with --nested, but pass with --nested --e2h0, I
need to investigate this.

Thanks,
Joey

[1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git kvm-arm64/nv-next (commit a35d752b17f4)
[2] https://git.kernel.org/pub/scm/linux/kernel/git/maz/kvmtool.git arm64/nv-6.13 (commit 5b6fe295ea7)
[3] https://lore.kernel.org/kvmarm/20250220141354.2565567-1-joey.gouly@arm.com/

Alexandru Elisei (2):
  arm64: micro-bench: use smc when at EL2
  arm64: selftest: update test for running at EL2

Joey Gouly (7):
  arm64: drop to EL1 if booted at EL2
  arm64: efi: initialise SCTLR_ELx fully
  arm64: efi: initialise the EL
  arm64: timer: use hypervisor timers when at EL2
  arm64: micro-bench: fix timer IRQ
  arm64: pmu: count EL2 cycles
  arm64: run at EL2 if supported

 arm/cstart64.S             | 56 ++++++++++++++++++++++++++++++++++++--
 arm/efi/crt0-efi-aarch64.S |  5 ++++
 arm/micro-bench.c          | 26 ++++++++++++++++--
 arm/pmu.c                  | 13 ++++++---
 arm/selftest.c             | 18 ++++++++----
 arm/timer.c                | 10 +++++--
 lib/acpi.h                 |  2 ++
 lib/arm/asm/setup.h        |  1 +
 lib/arm/asm/timer.h        | 11 ++++++++
 lib/arm/setup.c            |  6 ++++
 lib/arm/timer.c            | 19 +++++++++++--
 lib/arm64/asm/sysreg.h     | 19 +++++++++++++
 12 files changed, 167 insertions(+), 19 deletions(-)

-- 
2.25.1

[kvm-unit-tests PATCH v2 1/9] arm64: drop to EL1 if booted at EL2

[Joey Gouly]

EL2 is not currently supported, drop to EL1 to conitnue booting.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
---
 arm/cstart64.S         | 47 +++++++++++++++++++++++++++++++++++++++---
 lib/arm64/asm/sysreg.h | 14 +++++++++++++
 2 files changed, 58 insertions(+), 3 deletions(-)

diff --git a/arm/cstart64.S b/arm/cstart64.S
index 014c9c7b..79b93dd4 100644
--- a/arm/cstart64.S
+++ b/arm/cstart64.S
@@ -15,6 +15,46 @@
 #include <asm/thread_info.h>
 #include <asm/sysreg.h>
 
+.macro init_el, tmp
+	mrs	\tmp, CurrentEL
+	cmp	\tmp, CurrentEL_EL2
+	b.ne	1f
+	/* EL2 setup */
+	mrs	\tmp, mpidr_el1
+	msr	vmpidr_el2, \tmp
+	mrs	\tmp, midr_el1
+	msr	vpidr_el2, \tmp
+	/* clear trap registers */
+	mrs	\tmp, id_aa64mmfr0_el1
+	ubfx	\tmp, \tmp, #ID_AA64MMFR0_EL1_FGT_SHIFT, #4
+	cbz	\tmp, .Lskip_fgt_\@
+	mov	\tmp, #0
+	msr_s	SYS_HFGRTR_EL2, \tmp
+	msr_s	SYS_HFGWTR_EL2, \tmp
+	msr_s	SYS_HFGITR_EL2, \tmp
+	mrs	\tmp, id_aa64mmfr0_el1
+	ubfx	\tmp, \tmp, #ID_AA64MMFR0_EL1_FGT_SHIFT, #4
+	cmp	\tmp, #ID_AA64MMFR0_EL1_FGT_FGT2
+	bne	.Lskip_fgt_\@
+	mov	\tmp, #0
+	msr_s	SYS_HFGRTR2_EL2, \tmp
+	msr_s	SYS_HFGWTR2_EL2, \tmp
+	msr_s	SYS_HFGITR2_EL2, \tmp
+.Lskip_fgt_\@:
+	mov	\tmp, #0
+	msr	cptr_el2, \tmp
+	ldr	\tmp, =(INIT_HCR_EL2_EL1_ONLY)
+	msr	hcr_el2, \tmp
+	mov	\tmp, PSR_MODE_EL1t
+	msr	spsr_el2, \tmp
+	adrp	\tmp, 1f
+	add	\tmp, \tmp, :lo12:1f
+	msr	elr_el2, \tmp
+	eret
+1:
+.endm
+
+
 #ifdef CONFIG_EFI
 #include "efi/crt0-efi-aarch64.S"
 #else
@@ -56,15 +96,15 @@ start:
 	add     x6, x6, :lo12:reloc_end
 1:
 	cmp	x5, x6
-	b.hs	1f
+	b.hs	reloc_done
 	ldr	x7, [x5]			// r_offset
 	ldr	x8, [x5, #16]			// r_addend
 	add	x8, x8, x4			// val = base + r_addend
 	str	x8, [x4, x7]			// base[r_offset] = val
 	add	x5, x5, #24
 	b	1b
-
-1:
+reloc_done:
+	init_el x4
 	/* zero BSS */
 	adrp	x4, bss
 	add	x4, x4, :lo12:bss
@@ -185,6 +225,7 @@ get_mmu_off:
 
 .globl secondary_entry
 secondary_entry:
+	init_el x0
 	/* enable FP/ASIMD and SVE */
 	mov	x0, #(3 << 20)
 	orr	x0, x0, #(3 << 16)
diff --git a/lib/arm64/asm/sysreg.h b/lib/arm64/asm/sysreg.h
index e537bb46..ed776716 100644
--- a/lib/arm64/asm/sysreg.h
+++ b/lib/arm64/asm/sysreg.h
@@ -77,6 +77,9 @@ asm(
 #define ID_AA64ISAR0_EL1_RNDR_SHIFT	60
 #define ID_AA64PFR1_EL1_MTE_SHIFT	8
 
+#define ID_AA64MMFR0_EL1_FGT_SHIFT	56
+#define ID_AA64MMFR0_EL1_FGT_FGT2	0x2
+
 #define ICC_PMR_EL1			sys_reg(3, 0, 4, 6, 0)
 #define ICC_SGI1R_EL1			sys_reg(3, 0, 12, 11, 5)
 #define ICC_IAR1_EL1			sys_reg(3, 0, 12, 12, 0)
@@ -113,6 +116,17 @@ asm(
 #define SCTLR_EL1_TCF0_SHIFT	38
 #define SCTLR_EL1_TCF0_MASK	GENMASK_ULL(39, 38)
 
+#define HCR_EL2_RW		_BITULL(31)
+
+#define INIT_HCR_EL2_EL1_ONLY	(HCR_EL2_RW)
+
+#define SYS_HFGRTR_EL2		sys_reg(3, 4, 1, 1, 4)
+#define SYS_HFGWTR_EL2		sys_reg(3, 4, 1, 1, 5)
+#define SYS_HFGITR_EL2		sys_reg(3, 4, 1, 1, 6)
+#define SYS_HFGRTR2_EL2		sys_reg(3, 4, 3, 1, 2)
+#define SYS_HFGWTR2_EL2		sys_reg(3, 4, 3, 1, 3)
+#define SYS_HFGITR2_EL2		sys_reg(3, 4, 3, 1, 7)
+
 #define INIT_SCTLR_EL1_MMU_OFF	\
 			(SCTLR_EL1_ITD | SCTLR_EL1_SED | SCTLR_EL1_EOS | \
 			 SCTLR_EL1_TSCXT | SCTLR_EL1_EIS | SCTLR_EL1_SPAN | \
-- 
2.25.1

[kvm-unit-tests PATCH v2 2/9] arm64: efi: initialise SCTLR_ELx fully

[Joey Gouly]

Don't rely on the value of SCTLR_ELx when booting via EFI.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
---
 lib/arm/setup.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/arm/setup.c b/lib/arm/setup.c
index 67b5db07..0a22dbab 100644
--- a/lib/arm/setup.c
+++ b/lib/arm/setup.c
@@ -349,6 +349,11 @@ efi_status_t setup_efi(efi_bootinfo_t *efi_bootinfo)
 {
 	efi_status_t status;
 
+
+	// EFI exits boot services with SCTLR_ELx.M=1, so keep
+	// the MMU enabled.
+	write_sysreg(INIT_SCTLR_EL1_MMU_OFF | SCTLR_EL1_M, sctlr_el1);
+
 	exceptions_init();
 
 	memregions_init(arm_mem_regions, NR_MEM_REGIONS);
-- 
2.25.1

Re: [kvm-unit-tests PATCH v2 2/9] arm64: efi: initialise SCTLR_ELx fully

[Suzuki K Poulose]

On 29/05/2025 14:55, Joey Gouly wrote:
> Don't rely on the value of SCTLR_ELx when booting via EFI.
> 
> Signed-off-by: Joey Gouly <joey.gouly@arm.com>
> ---
>   lib/arm/setup.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/lib/arm/setup.c b/lib/arm/setup.c
> index 67b5db07..0a22dbab 100644
> --- a/lib/arm/setup.c
> +++ b/lib/arm/setup.c
> @@ -349,6 +349,11 @@ efi_status_t setup_efi(efi_bootinfo_t *efi_bootinfo)
>   {
>   	efi_status_t status;
>   
> +
> +	// EFI exits boot services with SCTLR_ELx.M=1, so keep
> +	// the MMU enabled.
> +	write_sysreg(INIT_SCTLR_EL1_MMU_OFF | SCTLR_EL1_M, sctlr_el1);

minor nit: Given this is in a common file for arm/arm64, may be worth 
adding a helper function that does this on arm64. I understand EFI
cannot enabled for arm32, still keeping this file generic would be
cleaner. e.g.,

mmu_on(); or even  setup_sctlr();

Suzuki

[kvm-unit-tests PATCH v2 3/9] arm64: efi: initialise the EL

[Joey Gouly]

Initialise the exception level, which may include dropping to EL1 from EL2, if
VHE is not supported.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
---
 arm/efi/crt0-efi-aarch64.S | 5 +++++
 lib/arm/asm/setup.h        | 1 +
 lib/arm/setup.c            | 1 +
 3 files changed, 7 insertions(+)

diff --git a/arm/efi/crt0-efi-aarch64.S b/arm/efi/crt0-efi-aarch64.S
index 71ce2794..5632fee0 100644
--- a/arm/efi/crt0-efi-aarch64.S
+++ b/arm/efi/crt0-efi-aarch64.S
@@ -147,6 +147,11 @@ _start:
 0:	ldp		x29, x30, [sp], #32
 	ret
 
+.globl do_init_el
+do_init_el:
+	init_el x16
+	ret
+
 	.section	.data
 
 .balign 65536
diff --git a/lib/arm/asm/setup.h b/lib/arm/asm/setup.h
index 9f8ef82e..6a409b38 100644
--- a/lib/arm/asm/setup.h
+++ b/lib/arm/asm/setup.h
@@ -28,6 +28,7 @@ void setup(const void *fdt, phys_addr_t freemem_start);
 
 #include <efi.h>
 
+void do_init_el(void);
 efi_status_t setup_efi(efi_bootinfo_t *efi_bootinfo);
 
 #endif
diff --git a/lib/arm/setup.c b/lib/arm/setup.c
index 0a22dbab..f49fa8ca 100644
--- a/lib/arm/setup.c
+++ b/lib/arm/setup.c
@@ -349,6 +349,7 @@ efi_status_t setup_efi(efi_bootinfo_t *efi_bootinfo)
 {
 	efi_status_t status;
 
+	do_init_el();
 
 	// EFI exits boot services with SCTLR_ELx.M=1, so keep
 	// the MMU enabled.
-- 
2.25.1

[kvm-unit-tests PATCH v2 4/9] arm64: timer: use hypervisor timers when at EL2

[Joey Gouly]

At EL2, with VHE:
  CNT{P,V}_{TVAL,CTL}_EL0 is forwarded to CNTH{P,V}_{CVAL,TVAL,CTL}_EL0.

Save the hypervisor physical and virtual timer IRQ numbers from the DT/ACPI.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 arm/timer.c         | 10 ++++++++--
 lib/acpi.h          |  2 ++
 lib/arm/asm/timer.h | 11 +++++++++++
 lib/arm/timer.c     | 19 +++++++++++++++++--
 4 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/arm/timer.c b/arm/timer.c
index 2cb80518..c6287ca7 100644
--- a/arm/timer.c
+++ b/arm/timer.c
@@ -347,8 +347,14 @@ static void test_ptimer(void)
 static void test_init(void)
 {
 	assert(TIMER_PTIMER_IRQ != -1 && TIMER_VTIMER_IRQ != -1);
-	ptimer_info.irq = TIMER_PTIMER_IRQ;
-	vtimer_info.irq = TIMER_VTIMER_IRQ;
+	if (current_level() == CurrentEL_EL1) {
+		ptimer_info.irq = TIMER_PTIMER_IRQ;
+		vtimer_info.irq = TIMER_VTIMER_IRQ;
+	} else {
+		assert(TIMER_HPTIMER_IRQ != -1 && TIMER_HVTIMER_IRQ != -1);
+		ptimer_info.irq = TIMER_HPTIMER_IRQ;
+		vtimer_info.irq = TIMER_HVTIMER_IRQ;
+	}
 
 	install_exception_handler(EL1H_SYNC, ESR_EL1_EC_UNKNOWN, ptimer_unsupported_handler);
 	ptimer_info.read_ctl();
diff --git a/lib/acpi.h b/lib/acpi.h
index c330c877..66e3062d 100644
--- a/lib/acpi.h
+++ b/lib/acpi.h
@@ -290,6 +290,8 @@ struct acpi_table_gtdt {
 	u64 counter_read_block_address;
 	u32 platform_timer_count;
 	u32 platform_timer_offset;
+	u32 virtual_el2_timer_interrupt;
+	u32 virtual_el2_timer_flags;
 };
 
 /* Reset to default packing */
diff --git a/lib/arm/asm/timer.h b/lib/arm/asm/timer.h
index fd8f7796..0dcebc1c 100644
--- a/lib/arm/asm/timer.h
+++ b/lib/arm/asm/timer.h
@@ -21,12 +21,23 @@ struct timer_state {
 		u32 irq;
 		u32 irq_flags;
 	} vtimer;
+	struct {
+		u32 irq;
+		u32 irq_flags;
+	} hptimer;
+	struct {
+		u32 irq;
+		u32 irq_flags;
+	} hvtimer;
 };
 extern struct timer_state __timer_state;
 
 #define TIMER_PTIMER_IRQ (__timer_state.ptimer.irq)
 #define TIMER_VTIMER_IRQ (__timer_state.vtimer.irq)
 
+#define TIMER_HPTIMER_IRQ (__timer_state.hptimer.irq)
+#define TIMER_HVTIMER_IRQ (__timer_state.hvtimer.irq)
+
 void timer_save_state(void);
 
 #endif /* !__ASSEMBLER__ */
diff --git a/lib/arm/timer.c b/lib/arm/timer.c
index ae702e41..57f504e2 100644
--- a/lib/arm/timer.c
+++ b/lib/arm/timer.c
@@ -38,10 +38,11 @@ static void timer_save_state_fdt(void)
 	 *      secure timer irq
 	 *      non-secure timer irq            (ptimer)
 	 *      virtual timer irq               (vtimer)
-	 *      hypervisor timer irq
+	 *      hypervisor timer irq            (hptimer)
+	 *      hypervisor virtual timer irq    (hvtimer)
 	 */
 	prop = fdt_get_property(fdt, node, "interrupts", &len);
-	assert(prop && len == (4 * 3 * sizeof(u32)));
+	assert(prop && len >= (4 * 3 * sizeof(u32)));
 
 	data = (u32 *) prop->data;
 	assert(fdt32_to_cpu(data[3]) == 1 /* PPI */ );
@@ -50,6 +51,14 @@ static void timer_save_state_fdt(void)
 	assert(fdt32_to_cpu(data[6]) == 1 /* PPI */ );
 	__timer_state.vtimer.irq = PPI(fdt32_to_cpu(data[7]));
 	__timer_state.vtimer.irq_flags = fdt32_to_cpu(data[8]);
+	if (len == (5 * 3 * sizeof(u32))) {
+		assert(fdt32_to_cpu(data[9]) == 1 /* PPI */ );
+		__timer_state.hptimer.irq = PPI(fdt32_to_cpu(data[10]));
+		__timer_state.hptimer.irq_flags = fdt32_to_cpu(data[11]);
+		assert(fdt32_to_cpu(data[12]) == 1 /* PPI */ );
+		__timer_state.hvtimer.irq = PPI(fdt32_to_cpu(data[13]));
+		__timer_state.hvtimer.irq_flags = fdt32_to_cpu(data[14]);
+	}
 }
 
 #ifdef CONFIG_EFI
@@ -72,6 +81,12 @@ static void timer_save_state_acpi(void)
 
 	__timer_state.vtimer.irq = gtdt->virtual_timer_interrupt;
 	__timer_state.vtimer.irq_flags = gtdt->virtual_timer_flags;
+
+	__timer_state.hptimer.irq = gtdt->non_secure_el2_interrupt;
+	__timer_state.hptimer.irq_flags = gtdt->non_secure_el2_flags;
+
+	__timer_state.hvtimer.irq = gtdt->virtual_el2_timer_interrupt;
+	__timer_state.hvtimer.irq_flags = gtdt->virtual_el2_timer_flags;
 }
 
 #else
-- 
2.25.1

[kvm-unit-tests PATCH v2 5/9] arm64: micro-bench: fix timer IRQ

[Joey Gouly]

Enable the correct (hvtimer) IRQ when at EL2.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 arm/micro-bench.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arm/micro-bench.c b/arm/micro-bench.c
index 22408955..f47c5fc1 100644
--- a/arm/micro-bench.c
+++ b/arm/micro-bench.c
@@ -42,7 +42,7 @@ static void gic_irq_handler(struct pt_regs *regs)
 	irq_received = true;
 	gic_write_eoir(irqstat);
 
-	if (irqstat == TIMER_VTIMER_IRQ) {
+	if (irqstat == TIMER_VTIMER_IRQ || irqstat == TIMER_HVTIMER_IRQ) {
 		write_sysreg((ARCH_TIMER_CTL_IMASK | ARCH_TIMER_CTL_ENABLE),
 			     cntv_ctl_el0);
 		isb();
@@ -215,7 +215,11 @@ static bool timer_prep(void)
 	install_irq_handler(EL1H_IRQ, gic_irq_handler);
 	local_irq_enable();
 
-	gic_enable_irq(TIMER_VTIMER_IRQ);
+	if (current_level() == CurrentEL_EL1)
+		gic_enable_irq(TIMER_VTIMER_IRQ);
+	else
+		gic_enable_irq(TIMER_HVTIMER_IRQ);
+
 	write_sysreg(ARCH_TIMER_CTL_IMASK | ARCH_TIMER_CTL_ENABLE, cntv_ctl_el0);
 	isb();
 
-- 
2.25.1

[kvm-unit-tests PATCH v2 6/9] arm64: micro-bench: use smc when at EL2

[Joey Gouly]

From: Alexandru Elisei <alexandru.elisei@arm.com>

At EL2, hvc would target the current EL, use smc so that it targets EL3.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
---
 arm/micro-bench.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/arm/micro-bench.c b/arm/micro-bench.c
index f47c5fc1..32029c5a 100644
--- a/arm/micro-bench.c
+++ b/arm/micro-bench.c
@@ -282,6 +282,11 @@ static bool mmio_read_user_prep(void)
 	return true;
 }
 
+static void smc_exec(void)
+{
+       asm volatile("mov w0, #0x4b000000; smc #0" ::: "w0");
+}
+
 static void mmio_read_user_exec(void)
 {
 	readl(userspace_emulated_addr);
@@ -300,6 +305,8 @@ static void eoi_exec(void)
 	write_eoir(spurious_id);
 }
 
+static bool exec_select(void);
+
 struct exit_test {
 	const char *name;
 	bool (*prep)(void);
@@ -310,7 +317,7 @@ struct exit_test {
 };
 
 static struct exit_test tests[] = {
-	{"hvc",			NULL,			hvc_exec,		NULL,		65536,		true},
+	{"hyp_call",		exec_select,		hvc_exec,		NULL,		65536,		true},
 	{"mmio_read_user",	mmio_read_user_prep,	mmio_read_user_exec,	NULL,		65536,		true},
 	{"mmio_read_vgic",	NULL,			mmio_read_vgic_exec,	NULL,		65536,		true},
 	{"eoi",			NULL,			eoi_exec,		NULL,		65536,		true},
@@ -320,6 +327,15 @@ static struct exit_test tests[] = {
 	{"timer_10ms",		timer_prep,		timer_exec,		timer_post,	256,		true},
 };
 
+static bool exec_select(void)
+{
+       if (current_level() == CurrentEL_EL2)
+               tests[0].exec = &smc_exec;
+       else
+               tests[0].exec = &hvc_exec;
+        return true;
+}
+
 struct ns_time {
 	uint64_t ns;
 	uint64_t ns_frac;
-- 
2.25.1

[kvm-unit-tests PATCH v2 7/9] arm64: selftest: update test for running at EL2

[Joey Gouly]

From: Alexandru Elisei <alexandru.elisei@arm.com>

Remove some hard-coded assumptions that this test is running at EL1.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
---
 arm/selftest.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/arm/selftest.c b/arm/selftest.c
index 1553ed8e..01691389 100644
--- a/arm/selftest.c
+++ b/arm/selftest.c
@@ -232,6 +232,7 @@ static void user_psci_system_off(struct pt_regs *regs)
 	__user_psci_system_off();
 }
 #elif defined(__aarch64__)
+static unsigned long expected_level;
 
 /*
  * Capture the current register state and execute an instruction
@@ -276,8 +277,7 @@ static bool check_regs(struct pt_regs *regs)
 {
 	unsigned i;
 
-	/* exception handlers should always run in EL1 */
-	if (current_level() != CurrentEL_EL1)
+	if (current_level() != expected_level)
 		return false;
 
 	for (i = 0; i < ARRAY_SIZE(regs->regs); ++i) {
@@ -301,7 +301,11 @@ static enum vector check_vector_prep(void)
 		return EL0_SYNC_64;
 
 	asm volatile("mrs %0, daif" : "=r" (daif) ::);
-	expected_regs.pstate = daif | PSR_MODE_EL1h;
+	expected_regs.pstate = daif;
+	if (current_level() == CurrentEL_EL1)
+		expected_regs.pstate |= PSR_MODE_EL1h;
+	else
+		expected_regs.pstate |= PSR_MODE_EL2h;
 	return EL1H_SYNC;
 }
 
@@ -317,8 +321,8 @@ static bool check_und(void)
 
 	install_exception_handler(v, ESR_EL1_EC_UNKNOWN, unknown_handler);
 
-	/* try to read an el2 sysreg from el0/1 */
-	test_exception("", "mrs x0, sctlr_el2", "", "x0");
+	/* try to read an el3 sysreg from el0/1/2 */
+	test_exception("", "mrs x0, sctlr_el3", "", "x0");
 
 	install_exception_handler(v, ESR_EL1_EC_UNKNOWN, NULL);
 
@@ -429,6 +433,10 @@ int main(int argc, char **argv)
 	if (argc < 2)
 		report_abort("no test specified");
 
+#if defined(__aarch64__)
+	expected_level = current_level();
+#endif
+
 	report_prefix_push(argv[1]);
 
 	if (strcmp(argv[1], "setup") == 0) {
-- 
2.25.1

[kvm-unit-tests PATCH v2 8/9] arm64: pmu: count EL2 cycles

[Joey Gouly]

Count EL2 cycles if that's the EL kvm-unit-tests is running at!

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
---
 arm/pmu.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/arm/pmu.c b/arm/pmu.c
index 2dc0822b..e6c0f05b 100644
--- a/arm/pmu.c
+++ b/arm/pmu.c
@@ -121,6 +121,8 @@ static struct pmu pmu;
 #define PMINTENCLR   __ACCESS_CP15(c9, 0, c14, 2)
 #define PMCCNTR64    __ACCESS_CP15_64(0, c9)
 
+#define PMCCFILTR_EL0_DEFAULT	0
+
 static inline uint32_t get_id_dfr0(void) { return read_sysreg(ID_DFR0); }
 static inline uint32_t get_pmcr(void) { return read_sysreg(PMCR); }
 static inline void set_pmcr(uint32_t v) { write_sysreg(v, PMCR); }
@@ -206,6 +208,9 @@ static void test_overflow_interrupt(bool overflow_at_64bits) {}
 #define ID_DFR0_PMU_V3_8_5	0b0110
 #define ID_DFR0_PMU_IMPDEF	0b1111
 
+#define PMCCFILTR_EL0_NSH	BIT(27)
+#define PMCCFILTR_EL0_DEFAULT	(current_level() == CurrentEL_EL2 ? PMCCFILTR_EL0_NSH : 0)
+
 static inline uint32_t get_id_aa64dfr0(void) { return read_sysreg(id_aa64dfr0_el1); }
 static inline uint32_t get_pmcr(void) { return read_sysreg(pmcr_el0); }
 static inline void set_pmcr(uint32_t v) { write_sysreg(v, pmcr_el0); }
@@ -246,8 +251,7 @@ static inline void precise_instrs_loop(int loop, uint32_t pmcr)
 #define PMCNTENSET_EL0 sys_reg(3, 3, 9, 12, 1)
 #define PMCNTENCLR_EL0 sys_reg(3, 3, 9, 12, 2)
 
-#define PMEVTYPER_EXCLUDE_EL1 BIT(31)
-#define PMEVTYPER_EXCLUDE_EL0 BIT(30)
+#define PMEVTYPER_EXCLUDE_EL0 BIT(30) | (current_level() == CurrentEL_EL2 ? BIT(27) : 0)
 
 static bool is_event_supported(uint32_t n, bool warn)
 {
@@ -1063,7 +1067,8 @@ static bool check_cycles_increase(void)
 	/* init before event access, this test only cares about cycle count */
 	pmu_reset();
 	set_pmcntenset(1 << PMU_CYCLE_IDX);
-	set_pmccfiltr(0); /* count cycles in EL0, EL1, but not EL2 */
+
+	set_pmccfiltr(PMCCFILTR_EL0_DEFAULT);
 
 	set_pmcr(get_pmcr() | PMU_PMCR_LC | PMU_PMCR_C | PMU_PMCR_E);
 	isb();
@@ -1118,7 +1123,7 @@ static bool check_cpi(int cpi)
 	/* init before event access, this test only cares about cycle count */
 	pmu_reset();
 	set_pmcntenset(1 << PMU_CYCLE_IDX);
-	set_pmccfiltr(0); /* count cycles in EL0, EL1, but not EL2 */
+	set_pmccfiltr(PMCCFILTR_EL0_DEFAULT);
 
 	if (cpi > 0)
 		printf("Checking for CPI=%d.\n", cpi);
-- 
2.25.1

[kvm-unit-tests PATCH v2 9/9] arm64: run at EL2 if supported

[Joey Gouly]

If VHE is supported, continue booting at EL2, otherwise continue booting at
EL1.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
---
 arm/cstart64.S         | 17 +++++++++++++----
 lib/arm64/asm/sysreg.h |  5 +++++
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/arm/cstart64.S b/arm/cstart64.S
index 79b93dd4..af7c81c1 100644
--- a/arm/cstart64.S
+++ b/arm/cstart64.S
@@ -18,7 +18,7 @@
 .macro init_el, tmp
 	mrs	\tmp, CurrentEL
 	cmp	\tmp, CurrentEL_EL2
-	b.ne	1f
+	b.ne	2f
 	/* EL2 setup */
 	mrs	\tmp, mpidr_el1
 	msr	vmpidr_el2, \tmp
@@ -41,17 +41,26 @@
 	msr_s	SYS_HFGWTR2_EL2, \tmp
 	msr_s	SYS_HFGITR2_EL2, \tmp
 .Lskip_fgt_\@:
+	/* check VHE is supported */
+	mrs	\tmp, ID_AA64MMFR1_EL1
+	ubfx	\tmp, \tmp, ID_AA64MMFR1_EL1_VH_SHIFT, #4
+	cbz	\tmp, 1f
+	ldr	\tmp, =(INIT_HCR_EL2)
+	msr	hcr_el2, \tmp
+	isb
+	b	2f
+1:
 	mov	\tmp, #0
 	msr	cptr_el2, \tmp
 	ldr	\tmp, =(INIT_HCR_EL2_EL1_ONLY)
 	msr	hcr_el2, \tmp
 	mov	\tmp, PSR_MODE_EL1t
 	msr	spsr_el2, \tmp
-	adrp	\tmp, 1f
-	add	\tmp, \tmp, :lo12:1f
+	adrp	\tmp, 2f
+	add	\tmp, \tmp, :lo12:2f
 	msr	elr_el2, \tmp
 	eret
-1:
+2:
 .endm
 
 
diff --git a/lib/arm64/asm/sysreg.h b/lib/arm64/asm/sysreg.h
index ed776716..f2d05018 100644
--- a/lib/arm64/asm/sysreg.h
+++ b/lib/arm64/asm/sysreg.h
@@ -80,6 +80,8 @@ asm(
 #define ID_AA64MMFR0_EL1_FGT_SHIFT	56
 #define ID_AA64MMFR0_EL1_FGT_FGT2	0x2
 
+#define ID_AA64MMFR1_EL1_VH_SHIFT	8
+
 #define ICC_PMR_EL1			sys_reg(3, 0, 4, 6, 0)
 #define ICC_SGI1R_EL1			sys_reg(3, 0, 12, 11, 5)
 #define ICC_IAR1_EL1			sys_reg(3, 0, 12, 12, 0)
@@ -116,9 +118,12 @@ asm(
 #define SCTLR_EL1_TCF0_SHIFT	38
 #define SCTLR_EL1_TCF0_MASK	GENMASK_ULL(39, 38)
 
+#define HCR_EL2_TGE		_BITULL(27)
 #define HCR_EL2_RW		_BITULL(31)
+#define HCR_EL2_E2H		_BITULL(34)
 
 #define INIT_HCR_EL2_EL1_ONLY	(HCR_EL2_RW)
+#define INIT_HCR_EL2		(HCR_EL2_TGE | HCR_EL2_E2H | HCR_EL2_RW)
 
 #define SYS_HFGRTR_EL2		sys_reg(3, 4, 1, 1, 4)
 #define SYS_HFGWTR_EL2		sys_reg(3, 4, 1, 1, 5)
-- 
2.25.1

Re: [kvm-unit-tests PATCH v2 0/9] arm64: support EL2

[Alexandru Elisei]

Hi Joey,

On Thu, May 29, 2025 at 02:55:48PM +0100, Joey Gouly wrote:
> Hi all,
> 
> This series is for adding support to running the kvm-unit-tests at EL2. These
> have been tested with Marc Zyngier's Linux kvm-arm64/nv-next branch [1] and
> kvmtool branch arm64/nv-6.13 [2]
> 
> The goal is to later extend and add new tests for Nested Virtualisation,
> however they should also work with bare metal as well.
> 
> Changes since v1[3]:
> 	- Authorship fixed on 2 patches
> 	- Tested and fixed EFI support
> 	- Recactored assembly and added init_el macro
> 	- Clear trap registers, trying to avoid relying on default register
> 	  state
> 	- Cleaned up PMU changes
> 
> The debug tests fail with --nested, but pass with --nested --e2h0, I
> need to investigate this.

That's because the code does not check for the absence of FEAT_E2H0, and it sets
HCR_EL2.E2H to 0 when writing INIT_HCR_EL2_EL1_ONLY even if KVM doesn't support
that.

Have you considered using parts of el2_setup.h as-is instead of rolling out your
own EL2 init code? When I was looking at the init_el macro I was comparing it
with el2_setup.h, and having some of the code shared would make things easier
with updates and fixes too.

Either way, not a deal breaker if you want to write your own init code.

Thanks,
Alex

> 
> Thanks,
> Joey
> 
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git kvm-arm64/nv-next (commit a35d752b17f4)
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/maz/kvmtool.git arm64/nv-6.13 (commit 5b6fe295ea7)
> [3] https://lore.kernel.org/kvmarm/20250220141354.2565567-1-joey.gouly@arm.com/
> 
> Alexandru Elisei (2):
>   arm64: micro-bench: use smc when at EL2
>   arm64: selftest: update test for running at EL2
> 
> Joey Gouly (7):
>   arm64: drop to EL1 if booted at EL2
>   arm64: efi: initialise SCTLR_ELx fully
>   arm64: efi: initialise the EL
>   arm64: timer: use hypervisor timers when at EL2
>   arm64: micro-bench: fix timer IRQ
>   arm64: pmu: count EL2 cycles
>   arm64: run at EL2 if supported
> 
>  arm/cstart64.S             | 56 ++++++++++++++++++++++++++++++++++++--
>  arm/efi/crt0-efi-aarch64.S |  5 ++++
>  arm/micro-bench.c          | 26 ++++++++++++++++--
>  arm/pmu.c                  | 13 ++++++---
>  arm/selftest.c             | 18 ++++++++----
>  arm/timer.c                | 10 +++++--
>  lib/acpi.h                 |  2 ++
>  lib/arm/asm/setup.h        |  1 +
>  lib/arm/asm/timer.h        | 11 ++++++++
>  lib/arm/setup.c            |  6 ++++
>  lib/arm/timer.c            | 19 +++++++++++--
>  lib/arm64/asm/sysreg.h     | 19 +++++++++++++
>  12 files changed, 167 insertions(+), 19 deletions(-)
> 
> -- 
> 2.25.1
> 

Re: [kvm-unit-tests PATCH v2 0/9] arm64: support EL2

[Joey Gouly]

On Mon, Jun 16, 2025 at 01:34:17PM +0100, Alexandru Elisei wrote:
> Hi Joey,
> 
> On Thu, May 29, 2025 at 02:55:48PM +0100, Joey Gouly wrote:
> > Hi all,
> > 
> > This series is for adding support to running the kvm-unit-tests at EL2. These
> > have been tested with Marc Zyngier's Linux kvm-arm64/nv-next branch [1] and
> > kvmtool branch arm64/nv-6.13 [2]
> > 
> > The goal is to later extend and add new tests for Nested Virtualisation,
> > however they should also work with bare metal as well.
> > 
> > Changes since v1[3]:
> > 	- Authorship fixed on 2 patches
> > 	- Tested and fixed EFI support
> > 	- Recactored assembly and added init_el macro
> > 	- Clear trap registers, trying to avoid relying on default register
> > 	  state
> > 	- Cleaned up PMU changes
> > 
> > The debug tests fail with --nested, but pass with --nested --e2h0, I
> > need to investigate this.
> 
> That's because the code does not check for the absence of FEAT_E2H0, and it sets
> HCR_EL2.E2H to 0 when writing INIT_HCR_EL2_EL1_ONLY even if KVM doesn't support
> that.

INIT_HCR_EL2_EL1_ONLY is only used if VHE is not supported, and if VHE is not
supported it's RES0. Patch 9 adds that.

> 
> Have you considered using parts of el2_setup.h as-is instead of rolling out your
> own EL2 init code? When I was looking at the init_el macro I was comparing it
> with el2_setup.h, and having some of the code shared would make things easier
> with updates and fixes too.
> 
> Either way, not a deal breaker if you want to write your own init code.

I'll look into it, making our own simplified el2_setup.h based on Linux's.

Thanks,
Joey

> 
> Thanks,
> Alex
> 
> > 
> > Thanks,
> > Joey
> > 
> > [1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git kvm-arm64/nv-next (commit a35d752b17f4)
> > [2] https://git.kernel.org/pub/scm/linux/kernel/git/maz/kvmtool.git arm64/nv-6.13 (commit 5b6fe295ea7)
> > [3] https://lore.kernel.org/kvmarm/20250220141354.2565567-1-joey.gouly@arm.com/
> > 
> > Alexandru Elisei (2):
> >   arm64: micro-bench: use smc when at EL2
> >   arm64: selftest: update test for running at EL2
> > 
> > Joey Gouly (7):
> >   arm64: drop to EL1 if booted at EL2
> >   arm64: efi: initialise SCTLR_ELx fully
> >   arm64: efi: initialise the EL
> >   arm64: timer: use hypervisor timers when at EL2
> >   arm64: micro-bench: fix timer IRQ
> >   arm64: pmu: count EL2 cycles
> >   arm64: run at EL2 if supported
> > 
> >  arm/cstart64.S             | 56 ++++++++++++++++++++++++++++++++++++--
> >  arm/efi/crt0-efi-aarch64.S |  5 ++++
> >  arm/micro-bench.c          | 26 ++++++++++++++++--
> >  arm/pmu.c                  | 13 ++++++---
> >  arm/selftest.c             | 18 ++++++++----
> >  arm/timer.c                | 10 +++++--
> >  lib/acpi.h                 |  2 ++
> >  lib/arm/asm/setup.h        |  1 +
> >  lib/arm/asm/timer.h        | 11 ++++++++
> >  lib/arm/setup.c            |  6 ++++
> >  lib/arm/timer.c            | 19 +++++++++++--
> >  lib/arm64/asm/sysreg.h     | 19 +++++++++++++
> >  12 files changed, 167 insertions(+), 19 deletions(-)
> > 
> > -- 
> > 2.25.1
> >