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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v12 09/15] vpci/header: program p2m with guest BAR view
On Tue, Jan 09, 2024 at 04:51:24PM -0500, Stewart Hildebrand wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
>
> Take into account guest's BAR view and program its p2m accordingly:
> gfn is guest's view of the BAR and mfn is the physical BAR value.
> This way hardware domain sees physical BAR values and guest sees
> emulated ones.
>
> Hardware domain continues getting the BARs identity mapped, while for
> domUs the BARs are mapped at the requested guest address without
> modifying the BAR address in the device PCI config space.
>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
> Signed-off-by: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
Some nits and a request to add an extra assert. If you agree:
Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> ---
> In v12:
> - Update guest_addr in rom_write()
> - Use unsigned long for start_mfn and map_mfn to reduce mfn_x() calls
> - Use existing vmsix_table_*() functions
> - Change vmsix_table_base() to use .guest_addr
> In v11:
> - Add vmsix_guest_table_addr() and vmsix_guest_table_base() functions
> to access guest's view of the VMSIx tables.
> - Use MFN (not GFN) to check access permissions
> - Move page offset check to this patch
> - Call rangeset_remove_range() with correct parameters
> In v10:
> - Moved GFN variable definition outside the loop in map_range()
> - Updated printk error message in map_range()
> - Now BAR address is always stored in bar->guest_addr, even for
> HW dom, this removes bunch of ugly is_hwdom() checks in modify_bars()
> - vmsix_table_base() now uses .guest_addr instead of .addr
> In v9:
> - Extended the commit message
> - Use bar->guest_addr in modify_bars
> - Extended printk error message in map_range
> - Moved map_data initialization so .bar can be initialized during declaration
> Since v5:
> - remove debug print in map_range callback
> - remove "identity" from the debug print
> Since v4:
> - moved start_{gfn|mfn} calculation into map_range
> - pass vpci_bar in the map_data instead of start_{gfn|mfn}
> - s/guest_addr/guest_reg
> Since v3:
> - updated comment (Roger)
> - removed gfn_add(map->start_gfn, rc); which is wrong
> - use v->domain instead of v->vpci.pdev->domain
> - removed odd e.g. in comment
> - s/d%d/%pd in altered code
> - use gdprintk for map/unmap logs
> Since v2:
> - improve readability for data.start_gfn and restructure ?: construct
> Since v1:
> - s/MSI/MSI-X in comments
> ---
> xen/drivers/vpci/header.c | 81 +++++++++++++++++++++++++++++++--------
> xen/include/xen/vpci.h | 3 +-
> 2 files changed, 66 insertions(+), 18 deletions(-)
>
> diff --git a/xen/drivers/vpci/header.c b/xen/drivers/vpci/header.c
> index feccd070ddd0..f0b0b64b0929 100644
> --- a/xen/drivers/vpci/header.c
> +++ b/xen/drivers/vpci/header.c
> @@ -34,6 +34,7 @@
>
> struct map_data {
> struct domain *d;
> + const struct vpci_bar *bar;
> bool map;
> };
>
> @@ -41,13 +42,24 @@ static int cf_check map_range(
> unsigned long s, unsigned long e, void *data, unsigned long *c)
> {
> const struct map_data *map = data;
> + /* Start address of the BAR as seen by the guest. */
> + unsigned long start_gfn = PFN_DOWN(map->bar->guest_addr);
> + /* Physical start address of the BAR. */
> + unsigned long start_mfn = PFN_DOWN(map->bar->addr);
> int rc;
>
> for ( ; ; )
> {
> unsigned long size = e - s + 1;
> + /*
> + * Ranges to be mapped don't always start at the BAR start address,
> as
> + * there can be holes or partially consumed ranges. Account for the
> + * offset of the current address from the BAR start.
> + */
> + unsigned long map_mfn = start_mfn + s - start_gfn;
> + unsigned long m_end = map_mfn + size - 1;
>
> - if ( !iomem_access_permitted(map->d, s, e) )
> + if ( !iomem_access_permitted(map->d, map_mfn, m_end) )
> {
> printk(XENLOG_G_WARNING
> "%pd denied access to MMIO range [%#lx, %#lx]\n",
> @@ -55,7 +67,8 @@ static int cf_check map_range(
> return -EPERM;
> }
>
> - rc = xsm_iomem_mapping(XSM_HOOK, map->d, s, e, map->map);
> + rc = xsm_iomem_mapping(XSM_HOOK, map->d, map_mfn, m_end,
> + map->map);
> if ( rc )
> {
> printk(XENLOG_G_WARNING
> @@ -73,8 +86,8 @@ static int cf_check map_range(
> * - {un}map_mmio_regions doesn't support preemption.
> */
>
> - rc = map->map ? map_mmio_regions(map->d, _gfn(s), size, _mfn(s))
> - : unmap_mmio_regions(map->d, _gfn(s), size, _mfn(s));
> + rc = map->map ? map_mmio_regions(map->d, _gfn(s), size,
> _mfn(map_mfn))
> + : unmap_mmio_regions(map->d, _gfn(s), size,
> _mfn(map_mfn));
> if ( rc == 0 )
> {
> *c += size;
> @@ -83,8 +96,9 @@ static int cf_check map_range(
> if ( rc < 0 )
> {
> printk(XENLOG_G_WARNING
> - "Failed to identity %smap [%lx, %lx] for d%d: %d\n",
> - map->map ? "" : "un", s, e, map->d->domain_id, rc);
> + "Failed to %smap [%lx %lx] -> [%lx %lx] for %pd: %d\n",
> + map->map ? "" : "un", s, e, map_mfn,
> + map_mfn + size, map->d, rc);
> break;
> }
> ASSERT(rc < size);
> @@ -163,10 +177,6 @@ static void modify_decoding(const struct pci_dev *pdev,
> uint16_t cmd,
> bool vpci_process_pending(struct vcpu *v)
> {
> struct pci_dev *pdev = v->vpci.pdev;
> - struct map_data data = {
> - .d = v->domain,
> - .map = v->vpci.cmd & PCI_COMMAND_MEMORY,
> - };
> struct vpci_header *header = NULL;
> unsigned int i;
>
> @@ -186,6 +196,11 @@ bool vpci_process_pending(struct vcpu *v)
> for ( i = 0; i < ARRAY_SIZE(header->bars); i++ )
> {
> struct vpci_bar *bar = &header->bars[i];
> + struct map_data data = {
> + .d = v->domain,
> + .map = v->vpci.cmd & PCI_COMMAND_MEMORY,
> + .bar = bar,
> + };
> int rc;
>
> if ( rangeset_is_empty(bar->mem) )
> @@ -236,7 +251,6 @@ bool vpci_process_pending(struct vcpu *v)
> static int __init apply_map(struct domain *d, const struct pci_dev *pdev,
> uint16_t cmd)
> {
> - struct map_data data = { .d = d, .map = true };
> struct vpci_header *header = &pdev->vpci->header;
> int rc = 0;
> unsigned int i;
> @@ -246,6 +260,7 @@ static int __init apply_map(struct domain *d, const
> struct pci_dev *pdev,
> for ( i = 0; i < ARRAY_SIZE(header->bars); i++ )
> {
> struct vpci_bar *bar = &header->bars[i];
> + struct map_data data = { .d = d, .map = true, .bar = bar };
>
> if ( rangeset_is_empty(bar->mem) )
> continue;
> @@ -311,12 +326,16 @@ static int modify_bars(const struct pci_dev *pdev,
> uint16_t cmd, bool rom_only)
> * First fill the rangesets with the BAR of this device or with the ROM
> * BAR only, depending on whether the guest is toggling the memory decode
> * bit of the command register, or the enable bit of the ROM BAR
> register.
> + *
> + * For non-hardware domain we use guest physical addresses.
> */
> for ( i = 0; i < ARRAY_SIZE(header->bars); i++ )
> {
> struct vpci_bar *bar = &header->bars[i];
> unsigned long start = PFN_DOWN(bar->addr);
> unsigned long end = PFN_DOWN(bar->addr + bar->size - 1);
> + unsigned long start_guest = PFN_DOWN(bar->guest_addr);
> + unsigned long end_guest = PFN_DOWN(bar->guest_addr + bar->size - 1);
>
> if ( !bar->mem )
> continue;
> @@ -336,11 +355,25 @@ static int modify_bars(const struct pci_dev *pdev,
> uint16_t cmd, bool rom_only)
> continue;
> }
Should we assert that the BAR rangeset is empty here? To stay on the
safe side.
>
> - rc = rangeset_add_range(bar->mem, start, end);
> + /*
> + * Make sure that the guest set address has the same page offset
> + * as the physical address on the host or otherwise things won't
> work as
> + * expected.
> + */
> + if ( PAGE_OFFSET(bar->guest_addr) != PAGE_OFFSET(bar->addr) )
> + {
> + gprintk(XENLOG_G_WARNING,
> + "%pp: Can't map BAR%d because of page offset mismatch:
> %lx vs %lx\n",
^u
Also when using the x modifier it's better to also use # to print the
0x prefix. You can also reduce the length of the message using
s/because of/due to/ IMO:
%pp: Can't map BAR%u due to offset mismatch: %lx vs %lx
> + &pdev->sbdf, i, PAGE_OFFSET(bar->guest_addr),
> + PAGE_OFFSET(bar->addr));
Maybe worth printing the whole address?
> + return -EINVAL;
> + }
> +
> + rc = rangeset_add_range(bar->mem, start_guest, end_guest);
> if ( rc )
> {
> printk(XENLOG_G_WARNING "Failed to add [%lx, %lx]: %d\n",
> - start, end, rc);
> + start_guest, end_guest, rc);
> return rc;
> }
>
> @@ -352,12 +385,12 @@ static int modify_bars(const struct pci_dev *pdev,
> uint16_t cmd, bool rom_only)
> if ( rangeset_is_empty(prev_bar->mem) )
> continue;
>
> - rc = rangeset_remove_range(prev_bar->mem, start, end);
> + rc = rangeset_remove_range(prev_bar->mem, start_guest,
> end_guest);
> if ( rc )
> {
> gprintk(XENLOG_WARNING,
> "%pp: failed to remove overlapping range [%lx, %lx]:
> %d\n",
> - &pdev->sbdf, start, end, rc);
> + &pdev->sbdf, start_guest, end_guest, rc);
> return rc;
> }
> }
> @@ -425,8 +458,8 @@ static int modify_bars(const struct pci_dev *pdev,
> uint16_t cmd, bool rom_only)
> for ( i = 0; i < ARRAY_SIZE(tmp->vpci->header.bars); i++ )
> {
> const struct vpci_bar *remote_bar =
> &tmp->vpci->header.bars[i];
> - unsigned long start = PFN_DOWN(remote_bar->addr);
> - unsigned long end = PFN_DOWN(remote_bar->addr +
> + unsigned long start = PFN_DOWN(remote_bar->guest_addr);
> + unsigned long end = PFN_DOWN(remote_bar->guest_addr +
> remote_bar->size - 1);
>
> if ( !remote_bar->enabled )
> @@ -513,6 +546,8 @@ static void cf_check bar_write(
> struct vpci_bar *bar = data;
> bool hi = false;
>
> + ASSERT(is_hardware_domain(pdev->domain));
> +
> if ( bar->type == VPCI_BAR_MEM64_HI )
> {
> ASSERT(reg > PCI_BASE_ADDRESS_0);
> @@ -543,6 +578,10 @@ static void cf_check bar_write(
> */
> bar->addr &= ~(0xffffffffULL << (hi ? 32 : 0));
> bar->addr |= (uint64_t)val << (hi ? 32 : 0);
> + /*
> + * Update guest address as well, so hardware domain sees BAR identity
> mapped
> + */
Can you drop the 'as well' and make this a single line comment?
Otherwise maybe reword to:
Update guest address, so hardware domain BAR is identity mapped.
Sorry, I find it wasteful to have the opening and closing comment
delimiters in separate lines for single line comments.
Thanks, Roger.
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