[PATCH v5 13/14] PCI: hv: Add hypercalls to read/write MMIO space

From: Michael Kelley <mikelley@microsoft.com>
To: hpa@zytor.com, kys@microsoft.com, haiyangz@microsoft.com,
	wei.liu@kernel.org, decui@microsoft.com, luto@kernel.org,
	peterz@infradead.org, davem@davemloft.net, edumazet@google.com,
	kuba@kernel.org, pabeni@redhat.com, lpieralisi@kernel.org,
	robh@kernel.org, kw@linux.com, bhelgaas@google.com,
	arnd@arndb.de, hch@lst.de, m.szyprowski@samsung.com,
	robin.murphy@arm.com, thomas.lendacky@amd.com,
	brijesh.singh@amd.com, tglx@linutronix.de, mingo@redhat.com,
	bp@alien8.de, dave.hansen@linux.intel.com,
	Tianyu.Lan@microsoft.com, kirill.shutemov@linux.intel.com,
	sathyanarayanan.kuppuswamy@linux.intel.com, ak@linux.intel.com,
	isaku.yamahata@intel.com, dan.j.williams@intel.com,
	jane.chu@oracle.com, seanjc@google.com, tony.luck@intel.com,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	linux-hyperv@vger.kernel.org, netdev@vger.kernel.org,
	linux-pci@vger.kernel.org, linux-arch@vger.kernel.org,
	iommu@lists.linux.dev
Cc: mikelley@microsoft.com
Subject: [PATCH v5 13/14] PCI: hv: Add hypercalls to read/write MMIO space
Date: Thu, 12 Jan 2023 13:42:32 -0800	[thread overview]
Message-ID: <1673559753-94403-14-git-send-email-mikelley@microsoft.com> (raw)
In-Reply-To: <1673559753-94403-1-git-send-email-mikelley@microsoft.com>

To support PCI pass-thru devices in Confidential VMs, Hyper-V
has added hypercalls to read and write MMIO space. Add the
appropriate definitions to hyperv-tlfs.h and implement
functions to make the hypercalls.

Co-developed-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
---
 arch/x86/include/asm/hyperv-tlfs.h  |  3 ++
 drivers/pci/controller/pci-hyperv.c | 64 +++++++++++++++++++++++++++++++++++++
 include/asm-generic/hyperv-tlfs.h   | 22 +++++++++++++
 3 files changed, 89 insertions(+)

diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 08e822b..db2202d9 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -119,6 +119,9 @@
 /* Recommend using enlightened VMCS */
 #define HV_X64_ENLIGHTENED_VMCS_RECOMMENDED		BIT(14)
 
+/* Use hypercalls for MMIO config space access */
+#define HV_X64_USE_MMIO_HYPERCALLS			BIT(21)
+
 /*
  * CPU management features identification.
  * These are HYPERV_CPUID_CPU_MANAGEMENT_FEATURES.EAX bits.
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 084f531..bbe6e36 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -1041,6 +1041,70 @@ static int wslot_to_devfn(u32 wslot)
 	return PCI_DEVFN(slot_no.bits.dev, slot_no.bits.func);
 }
 
+static void hv_pci_read_mmio(struct device *dev, phys_addr_t gpa, int size, u32 *val)
+{
+	struct hv_mmio_read_input *in;
+	struct hv_mmio_read_output *out;
+	u64 ret;
+
+	/*
+	 * Must be called with interrupts disabled so it is safe
+	 * to use the per-cpu input argument page.  Use it for
+	 * both input and output.
+	 */
+	in = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	out = *this_cpu_ptr(hyperv_pcpu_input_arg) + sizeof(*in);
+	in->gpa = gpa;
+	in->size = size;
+
+	ret = hv_do_hypercall(HVCALL_MMIO_READ, in, out);
+	if (hv_result_success(ret)) {
+		switch (size) {
+		case 1:
+			*val = *(u8 *)(out->data);
+			break;
+		case 2:
+			*val = *(u16 *)(out->data);
+			break;
+		default:
+			*val = *(u32 *)(out->data);
+			break;
+		}
+	} else
+		dev_err(dev, "MMIO read hypercall error %llx addr %llx size %d\n",
+				ret, gpa, size);
+}
+
+static void hv_pci_write_mmio(struct device *dev, phys_addr_t gpa, int size, u32 val)
+{
+	struct hv_mmio_write_input *in;
+	u64 ret;
+
+	/*
+	 * Must be called with interrupts disabled so it is safe
+	 * to use the per-cpu input argument memory.
+	 */
+	in = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	in->gpa = gpa;
+	in->size = size;
+	switch (size) {
+	case 1:
+		*(u8 *)(in->data) = val;
+		break;
+	case 2:
+		*(u16 *)(in->data) = val;
+		break;
+	default:
+		*(u32 *)(in->data) = val;
+		break;
+	}
+
+	ret = hv_do_hypercall(HVCALL_MMIO_WRITE, in, NULL);
+	if (!hv_result_success(ret))
+		dev_err(dev, "MMIO write hypercall error %llx addr %llx size %d\n",
+				ret, gpa, size);
+}
+
 /*
  * PCI Configuration Space for these root PCI buses is implemented as a pair
  * of pages in memory-mapped I/O space.  Writing to the first page chooses
diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index e29ccab..c1cc3ec 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -168,6 +168,8 @@ struct ms_hyperv_tsc_page {
 #define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_SPACE 0x00af
 #define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_LIST 0x00b0
 #define HVCALL_MODIFY_SPARSE_GPA_PAGE_HOST_VISIBILITY 0x00db
+#define HVCALL_MMIO_READ			0x0106
+#define HVCALL_MMIO_WRITE			0x0107
 
 /* Extended hypercalls */
 #define HV_EXT_CALL_QUERY_CAPABILITIES		0x8001
@@ -795,4 +797,24 @@ struct hv_memory_hint {
 	union hv_gpa_page_range ranges[];
 } __packed;
 
+/* Data structures for HVCALL_MMIO_READ and HVCALL_MMIO_WRITE */
+#define HV_HYPERCALL_MMIO_MAX_DATA_LENGTH 64
+
+struct hv_mmio_read_input {
+	u64 gpa;
+	u32 size;
+	u32 reserved;
+} __packed;
+
+struct hv_mmio_read_output {
+	u8 data[HV_HYPERCALL_MMIO_MAX_DATA_LENGTH];
+} __packed;
+
+struct hv_mmio_write_input {
+	u64 gpa;
+	u32 size;
+	u32 reserved;
+	u8 data[HV_HYPERCALL_MMIO_MAX_DATA_LENGTH];
+} __packed;
+
 #endif
-- 
1.8.3.1

