On 4/14/2025 7:32 AM, Alejandro Jimenez wrote:
The size of the region to invalidate depends on the S bit and address
encoded in the command. Add a helper to extract this information, which
will be used to sync shadow page tables in upcoming changes.
Signed-off-by: Alejandro Jimenez <alejandro.j.jime...@oracle.com>
---
hw/i386/amd_iommu.c | 34 ++++++++++++++++++++++++++++++++++
hw/i386/amd_iommu.h | 4 ++++
2 files changed, 38 insertions(+)
diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c
index 5f55be1f4d36..0af873b66a31 100644
--- a/hw/i386/amd_iommu.c
+++ b/hw/i386/amd_iommu.c
@@ -481,6 +481,40 @@ static gboolean amdvi_iotlb_remove_by_domid(gpointer key,
gpointer value,
return entry->domid == domid;
}
+/*
+ * Helper to decode the size of the range to invalidate encoded in the
+ * INVALIDATE_IOMMU_PAGES Command format.
+ * The size of the region to invalidate depends on the S bit and address.
+ * S bit value:
+ * 0 : Invalidation size is 4 Kbytes.
+ * 1 : Invalidation size is determined by first zero bit in the address
+ * starting from Address[12].
+ *
+ * In the AMD IOMMU Linux driver, an invalidation command with address
+ * ((1 << 63) - 1) is sent when intending to clear the entire cache.
+ * However, Table 14: Example Page Size Encodings shows that an address of
+ * ((1ULL << 51) - 1) encodes the entire cache, so effectively any address with
+ * first zero at bit 51 or larger is a request to invalidate the entire address
+ * space.
+ */
+static uint64_t __attribute__((unused))
+amdvi_decode_invalidation_size(hwaddr addr, uint16_t flags)
+{
+ uint64_t size = AMDVI_PAGE_SIZE;
+ uint8_t fzbit = 0;
+
+ if (flags & AMDVI_CMD_INVAL_IOMMU_PAGES_S) {
+ fzbit = cto64(addr | 0xFFF);
+
+ if (fzbit >= 51 || !addr) {
I am skeptical about the condition addr == 0 (!addr)
Consider the case where user wants to invalidate 8K size page, starting
from address 0. It'll cause address field to be 0, right ? If so, then
we should invalidate only 8K page not the entire address range.
Am I missing something here ?
Regards
Sairaj
+ size = AMDVI_INV_ALL_PAGES;
+ } else {> + size = 1ULL << (fzbit + 1);
+ }
+ }
+ return size;
+}
+
/* we don't have devid - we can't remove pages by address */
static void amdvi_inval_pages(AMDVIState *s, uint64_t *cmd)
{
diff --git a/hw/i386/amd_iommu.h b/hw/i386/amd_iommu.h
index e12ecade4baa..c89e7dc9947d 100644
--- a/hw/i386/amd_iommu.h
+++ b/hw/i386/amd_iommu.h
@@ -123,6 +123,10 @@
#define AMDVI_CMD_COMPLETE_PPR_REQUEST 0x07
#define AMDVI_CMD_INVAL_AMDVI_ALL 0x08
+
+#define AMDVI_CMD_INVAL_IOMMU_PAGES_S (1ULL << 0)
+#define AMDVI_INV_ALL_PAGES (1ULL << 52)
+
#define AMDVI_DEVTAB_ENTRY_SIZE 32
/* Device table entry bits 0:63 */
