linux-kernel - [PATCH v1 4/5] arm64/kvm: support to handle the HDBSSF event

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Message-ID: <20250311040321.1460-5-yezhenyu2@huawei.com>
Date: Tue, 11 Mar 2025 12:03:20 +0800
From: Zhenyu Ye <yezhenyu2@...wei.com>
To: <maz@...nel.org>, <yuzenghui@...wei.com>, <will@...nel.org>,
	<oliver.upton@...ux.dev>, <catalin.marinas@....com>, <joey.gouly@....com>
CC: <linux-kernel@...r.kernel.org>, <yezhenyu2@...wei.com>,
	<xiexiangyou@...wei.com>, <zhengchuan@...wei.com>, <wangzhou1@...ilicon.com>,
	<linux-arm-kernel@...ts.infradead.org>, <kvm@...r.kernel.org>,
	<kvmarm@...ts.linux.dev>
Subject: [PATCH v1 4/5] arm64/kvm: support to handle the HDBSSF event

From: eillon <yezhenyu2@...wei.com>

Updating the dirty bitmap based on the HDBSS buffer. Similar
to the implementation of the x86 pml feature, KVM flushes the
buffers on all VM-Exits, thus we only need to kick running
vCPUs to force a VM-Exit.

Signed-off-by: eillon <yezhenyu2@...wei.com>
---
 arch/arm64/kvm/arm.c         | 10 ++++++++
 arch/arm64/kvm/handle_exit.c | 47 ++++++++++++++++++++++++++++++++++++
 arch/arm64/kvm/mmu.c         |  7 ++++++
 3 files changed, 64 insertions(+)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 825cfef3b1c2..fceceeead011 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1845,7 +1845,17 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 
 void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
 {
+	/*
+	 * Flush all CPUs' dirty log buffers to the dirty_bitmap.  Called
+	 * before reporting dirty_bitmap to userspace.  KVM flushes the buffers
+	 * on all VM-Exits, thus we only need to kick running vCPUs to force a
+	 * VM-Exit.
+	 */
+	struct kvm_vcpu *vcpu;
+	unsigned long i;
 
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		kvm_vcpu_kick(vcpu);
 }
 
 static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm,
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index 512d152233ff..db9d7e1f72bf 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -330,6 +330,50 @@ static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
 	return arm_exit_handlers[esr_ec];
 }
 
+#define HDBSS_ENTRY_VALID_SHIFT 0
+#define HDBSS_ENTRY_VALID_MASK (1UL << HDBSS_ENTRY_VALID_SHIFT)
+#define HDBSS_ENTRY_IPA_SHIFT 12
+#define HDBSS_ENTRY_IPA_MASK GENMASK_ULL(55, HDBSS_ENTRY_IPA_SHIFT)
+
+static void kvm_flush_hdbss_buffer(struct kvm_vcpu *vcpu)
+{
+	int idx, curr_idx;
+	u64 *hdbss_buf;
+
+	if (!vcpu->kvm->enable_hdbss)
+		return;
+
+	dsb(sy);
+	isb();
+	curr_idx = HDBSSPROD_IDX(read_sysreg_s(SYS_HDBSSPROD_EL2));
+
+	/* Do nothing if HDBSS buffer is empty or br_el2 is NULL */
+	if (curr_idx == 0 || vcpu->arch.hdbss.br_el2 == 0)
+		return;
+
+	hdbss_buf = page_address(phys_to_page(HDBSSBR_BADDR(vcpu->arch.hdbss.br_el2)));
+	if (!hdbss_buf) {
+		kvm_err("Enter flush hdbss buffer with buffer == NULL!");
+		return;
+	}
+
+	for (idx = 0; idx < curr_idx; idx++) {
+		u64 gpa;
+
+		gpa = hdbss_buf[idx];
+		if (!(gpa & HDBSS_ENTRY_VALID_MASK))
+			continue;
+
+		gpa = gpa & HDBSS_ENTRY_IPA_MASK;
+		kvm_vcpu_mark_page_dirty(vcpu, gpa >> PAGE_SHIFT);
+	}
+
+	/* reset HDBSS index */
+	write_sysreg_s(0, SYS_HDBSSPROD_EL2);
+	dsb(sy);
+	isb();
+}
+
 /*
  * We may be single-stepping an emulated instruction. If the emulation
  * has been completed in the kernel, we can return to userspace with a
@@ -365,6 +409,9 @@ int handle_exit(struct kvm_vcpu *vcpu, int exception_index)
 {
 	struct kvm_run *run = vcpu->run;
 
+	if (vcpu->kvm->enable_hdbss)
+		kvm_flush_hdbss_buffer(vcpu);
+
 	if (ARM_SERROR_PENDING(exception_index)) {
 		/*
 		 * The SError is handled by handle_exit_early(). If the guest
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 9c11e2292b1e..3e0781ae0ae1 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1790,6 +1790,13 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
 	ipa = fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
 	is_iabt = kvm_vcpu_trap_is_iabt(vcpu);
 
+	/*
+	 * HDBSS buffer already flushed when enter handle_trap_exceptions().
+	 * Nothing to do here.
+	 */
+	if (ESR_ELx_ISS2(esr) & ESR_ELx_HDBSSF)
+		return 1;
+
 	if (esr_fsc_is_translation_fault(esr)) {
 		/* Beyond sanitised PARange (which is the IPA limit) */
 		if (fault_ipa >= BIT_ULL(get_kvm_ipa_limit())) {
-- 
2.39.3