1 files changed, 140 insertions, 12 deletions

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 7b5af6176de9..5140c820bda6 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -710,6 +710,26 @@ static void __init free_alias_table(struct amd_iommu_pci_seg *pci_seg)
 	pci_seg->alias_table = NULL;
 }
 
+static inline void *iommu_memremap(unsigned long paddr, size_t size)
+{
+	phys_addr_t phys;
+
+	if (!paddr)
+		return NULL;
+
+	/*
+	 * Obtain true physical address in kdump kernel when SME is enabled.
+	 * Currently, previous kernel with SME enabled and kdump kernel
+	 * with SME support disabled is not supported.
+	 */
+	phys = __sme_clr(paddr);
+
+	if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
+		return (__force void *)ioremap_encrypted(phys, size);
+	else
+		return memremap(phys, size, MEMREMAP_WB);
+}
+
 /*
  * Allocates the command buffer. This buffer is per AMD IOMMU. We can
  * write commands to that buffer later and the IOMMU will execute them
@@ -942,8 +962,91 @@ err_out:
 static int __init alloc_cwwb_sem(struct amd_iommu *iommu)
 {
 	iommu->cmd_sem = iommu_alloc_4k_pages(iommu, GFP_KERNEL, 1);
+	if (!iommu->cmd_sem)
+		return -ENOMEM;
+	iommu->cmd_sem_paddr = iommu_virt_to_phys((void *)iommu->cmd_sem);
+	return 0;
+}
+
+static int __init remap_event_buffer(struct amd_iommu *iommu)
+{
+	u64 paddr;
+
+	pr_info_once("Re-using event buffer from the previous kernel\n");
+	paddr = readq(iommu->mmio_base + MMIO_EVT_BUF_OFFSET) & PM_ADDR_MASK;
+	iommu->evt_buf = iommu_memremap(paddr, EVT_BUFFER_SIZE);
+
+	return iommu->evt_buf ? 0 : -ENOMEM;
+}
+
+static int __init remap_command_buffer(struct amd_iommu *iommu)
+{
+	u64 paddr;
 
-	return iommu->cmd_sem ? 0 : -ENOMEM;
+	pr_info_once("Re-using command buffer from the previous kernel\n");
+	paddr = readq(iommu->mmio_base + MMIO_CMD_BUF_OFFSET) & PM_ADDR_MASK;
+	iommu->cmd_buf = iommu_memremap(paddr, CMD_BUFFER_SIZE);
+
+	return iommu->cmd_buf ? 0 : -ENOMEM;
+}
+
+static int __init remap_or_alloc_cwwb_sem(struct amd_iommu *iommu)
+{
+	u64 paddr;
+
+	if (check_feature(FEATURE_SNP)) {
+		/*
+		 * When SNP is enabled, the exclusion base register is used for the
+		 * completion wait buffer (CWB) address. Read and re-use it.
+		 */
+		pr_info_once("Re-using CWB buffers from the previous kernel\n");
+		paddr = readq(iommu->mmio_base + MMIO_EXCL_BASE_OFFSET) & PM_ADDR_MASK;
+		iommu->cmd_sem = iommu_memremap(paddr, PAGE_SIZE);
+		if (!iommu->cmd_sem)
+			return -ENOMEM;
+		iommu->cmd_sem_paddr = paddr;
+	} else {
+		return alloc_cwwb_sem(iommu);
+	}
+
+	return 0;
+}
+
+static int __init alloc_iommu_buffers(struct amd_iommu *iommu)
+{
+	int ret;
+
+	/*
+	 * Reuse/Remap the previous kernel's allocated completion wait
+	 * command and event buffers for kdump boot.
+	 */
+	if (is_kdump_kernel()) {
+		ret = remap_or_alloc_cwwb_sem(iommu);
+		if (ret)
+			return ret;
+
+		ret = remap_command_buffer(iommu);
+		if (ret)
+			return ret;
+
+		ret = remap_event_buffer(iommu);
+		if (ret)
+			return ret;
+	} else {
+		ret = alloc_cwwb_sem(iommu);
+		if (ret)
+			return ret;
+
+		ret = alloc_command_buffer(iommu);
+		if (ret)
+			return ret;
+
+		ret = alloc_event_buffer(iommu);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
 }
 
 static void __init free_cwwb_sem(struct amd_iommu *iommu)
@@ -951,6 +1054,38 @@ static void __init free_cwwb_sem(struct amd_iommu *iommu)
 	if (iommu->cmd_sem)
 		iommu_free_pages((void *)iommu->cmd_sem);
 }
+static void __init unmap_cwwb_sem(struct amd_iommu *iommu)
+{
+	if (iommu->cmd_sem) {
+		if (check_feature(FEATURE_SNP))
+			memunmap((void *)iommu->cmd_sem);
+		else
+			iommu_free_pages((void *)iommu->cmd_sem);
+	}
+}
+
+static void __init unmap_command_buffer(struct amd_iommu *iommu)
+{
+	memunmap((void *)iommu->cmd_buf);
+}
+
+static void __init unmap_event_buffer(struct amd_iommu *iommu)
+{
+	memunmap(iommu->evt_buf);
+}
+
+static void __init free_iommu_buffers(struct amd_iommu *iommu)
+{
+	if (is_kdump_kernel()) {
+		unmap_cwwb_sem(iommu);
+		unmap_command_buffer(iommu);
+		unmap_event_buffer(iommu);
+	} else {
+		free_cwwb_sem(iommu);
+		free_command_buffer(iommu);
+		free_event_buffer(iommu);
+	}
+}
 
 static void iommu_enable_xt(struct amd_iommu *iommu)
 {
@@ -1655,9 +1790,7 @@ static void __init free_sysfs(struct amd_iommu *iommu)
 static void __init free_iommu_one(struct amd_iommu *iommu)
 {
 	free_sysfs(iommu);
-	free_cwwb_sem(iommu);
-	free_command_buffer(iommu);
-	free_event_buffer(iommu);
+	free_iommu_buffers(iommu);
 	amd_iommu_free_ppr_log(iommu);
 	free_ga_log(iommu);
 	iommu_unmap_mmio_space(iommu);
@@ -1821,14 +1954,9 @@ static int __init init_iommu_one_late(struct amd_iommu *iommu)
 {
 	int ret;
 
-	if (alloc_cwwb_sem(iommu))
-		return -ENOMEM;
-
-	if (alloc_command_buffer(iommu))
-		return -ENOMEM;
-
-	if (alloc_event_buffer(iommu))
-		return -ENOMEM;
+	ret = alloc_iommu_buffers(iommu);
+	if (ret)
+		return ret;
 
 	iommu->int_enabled = false;