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amd_iommu: Add helper function to extract the DTE

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Extracting the DTE from a given AMDVIAddressSpace pointer structure is a
common operation required for syncing the shadow page tables. Implement a
helper to do it and check for common error conditions.

Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20250919213515.917111-6-alejandro.j.jimenez@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Alejandro Jimenez 2025-09-19 21:34:58 +00:00 • committed by Michael S. Tsirkin
parent e8992fee66
commit 786d118530
1 changed files with 42 additions and 6 deletions
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48
hw/i386/amd_iommu.c
View file

@ -77,6 +77,18 @@ typedef struct AMDVIIOTLBEntry {
uint64_t page_mask; /* physical page size */
} AMDVIIOTLBEntry;
/*
* These 'fault' reasons have an overloaded meaning since they are not only
* intended for describing reasons that generate an IO_PAGE_FAULT as per the AMD
* IOMMU specification, but are also used to signal internal errors in the
* emulation code.
*/
typedef enum AMDVIFaultReason {
AMDVI_FR_DTE_RTR_ERR = 1, /* Failure to retrieve DTE */
AMDVI_FR_DTE_V, /* DTE[V] = 0 */
AMDVI_FR_DTE_TV, /* DTE[TV] = 0 */
} AMDVIFaultReason;
uint64_t amdvi_extended_feature_register(AMDVIState *s)
{
uint64_t feature = AMDVI_DEFAULT_EXT_FEATURES;
@ -524,6 +536,28 @@ static inline uint64_t amdvi_get_pte_entry(AMDVIState *s, uint64_t pte_addr,
return pte;
}
static int amdvi_as_to_dte(AMDVIAddressSpace *as, uint64_t *dte)
{
uint16_t devid = PCI_BUILD_BDF(as->bus_num, as->devfn);
AMDVIState *s = as->iommu_state;
if (!amdvi_get_dte(s, devid, dte)) {
/* Unable to retrieve DTE for devid */
return -AMDVI_FR_DTE_RTR_ERR;
}
if (!(dte[0] & AMDVI_DEV_VALID)) {
/* DTE[V] not set, address is passed untranslated for devid */
return -AMDVI_FR_DTE_V;
}
if (!(dte[0] & AMDVI_DEV_TRANSLATION_VALID)) {
/* DTE[TV] not set, host page table not valid for devid */
return -AMDVI_FR_DTE_TV;
}
return 0;
}
/* log error without aborting since linux seems to be using reserved bits */
static void amdvi_inval_devtab_entry(AMDVIState *s, uint64_t *cmd)
{
@ -1081,6 +1115,7 @@ static void amdvi_do_translate(AMDVIAddressSpace *as, hwaddr addr,
uint16_t devid = PCI_BUILD_BDF(as->bus_num, as->devfn);
AMDVIIOTLBEntry *iotlb_entry = amdvi_iotlb_lookup(s, addr, devid);
uint64_t entry[4];
int dte_ret;
if (iotlb_entry) {
trace_amdvi_iotlb_hit(PCI_BUS_NUM(devid), PCI_SLOT(devid),
@ -1092,13 +1127,14 @@ static void amdvi_do_translate(AMDVIAddressSpace *as, hwaddr addr,
return;
}
if (!amdvi_get_dte(s, devid, entry)) {
return;
}
dte_ret = amdvi_as_to_dte(as, entry);
/* devices with V = 0 are not translated */
if (!(entry[0] & AMDVI_DEV_VALID)) {
goto out;
if (dte_ret < 0) {
if (dte_ret == -AMDVI_FR_DTE_V) {
/* DTE[V]=0, address is passed untranslated */
goto out;
}
return;
}
amdvi_page_walk(as, entry, ret,