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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v2] Add support for ESRT loading under Xen
On Sun, 28 Aug 2022 at 04:52, Demi Marie Obenour
<demi@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> This is needed for fwupd to work in Qubes OS.
>
Please elaborate on:
- the current situation
- why this is a problem
- why your approach is a reasonable solution.
> Signed-off-by: Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>
> ---
> Changes since v1:
>
> - Use a different type (struct xen_efi_mem_info) for memory information
> provided by Xen, as Xen reports it in a different way than the
> standard Linux functions do.
>
> drivers/firmware/efi/esrt.c | 49 +++++++++++++++++++++++++++----------
> drivers/xen/efi.c | 32 ++++++++++++++++++++++++++
> include/linux/efi.h | 18 ++++++++++++++
> 3 files changed, 86 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/firmware/efi/esrt.c b/drivers/firmware/efi/esrt.c
> index
> 2a2f52b017e736dd995c69e8aeb5fbd7761732e5..c0fc149a838044cc16bb08a374a0c8ea6b7dcbff
> 100644
> --- a/drivers/firmware/efi/esrt.c
> +++ b/drivers/firmware/efi/esrt.c
> @@ -243,27 +243,50 @@ void __init efi_esrt_init(void)
> void *va;
> struct efi_system_resource_table tmpesrt;
> size_t size, max, entry_size, entries_size;
> - efi_memory_desc_t md;
> - int rc;
> phys_addr_t end;
> -
> - if (!efi_enabled(EFI_MEMMAP))
> - return;
> + uint32_t type;
>
> pr_debug("esrt-init: loading.\n");
> if (!esrt_table_exists())
> return;
>
> - rc = efi_mem_desc_lookup(efi.esrt, &md);
> - if (rc < 0 ||
> - (!(md.attribute & EFI_MEMORY_RUNTIME) &&
> - md.type != EFI_BOOT_SERVICES_DATA &&
> - md.type != EFI_RUNTIME_SERVICES_DATA)) {
> - pr_warn("ESRT header is not in the memory map.\n");
> + if (efi_enabled(EFI_MEMMAP)) {
> + efi_memory_desc_t md;
> +
> + if (efi_mem_desc_lookup(efi.esrt, &md) < 0 ||
> + (!(md.attribute & EFI_MEMORY_RUNTIME) &&
> + md.type != EFI_BOOT_SERVICES_DATA &&
> + md.type != EFI_RUNTIME_SERVICES_DATA)) {
> + pr_warn("ESRT header is not in the memory map.\n");
> + return;
> + }
> +
> + type = md.type;
> + max = efi_mem_desc_end(&md);
> + } else if (IS_ENABLED(CONFIG_XEN_EFI) && efi_enabled(EFI_PARAVIRT)) {
> + struct xen_efi_mem_info info;
> +
> + if (!xen_efi_mem_info_query(efi.esrt, &info)) {
> + pr_warn("Failed to lookup ESRT header in Xen memory
> map\n");
> + return;
> + }
> +
> + type = info.type;
> + max = info.addr + info.size;
> +
> + /* Recent Xen versions relocate the ESRT to memory of type
> + * EfiRuntimeServicesData, which Xen will not reuse. If the
> ESRT
This violates the EFI spec, which spells out very clearly that the
ESRT must be in EfiBootServicesData memory. Why are you deviating from
this?
> + * is not in EfiRuntimeServicesData memory, it has not been
> reserved
> + * by Xen and might be allocated to other guests, so it cannot
> + * safely be used. */
> + if (type != EFI_RUNTIME_SERVICES_DATA) {
> + pr_warn("Xen did not reserve ESRT, ignoring it\n");
> + return;
> + }
> + } else {
> return;
> }
>
> - max = efi_mem_desc_end(&md);
> if (max < efi.esrt) {
> pr_err("EFI memory descriptor is invalid. (esrt: %p max:
> %p)\n",
> (void *)efi.esrt, (void *)max);
> @@ -333,7 +356,7 @@ void __init efi_esrt_init(void)
>
> end = esrt_data + size;
> pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end);
> - if (md.type == EFI_BOOT_SERVICES_DATA)
> + if (type == EFI_BOOT_SERVICES_DATA)
> efi_mem_reserve(esrt_data, esrt_data_size);
>
> pr_debug("esrt-init: loaded.\n");
> diff --git a/drivers/xen/efi.c b/drivers/xen/efi.c
> index
> d1ff2186ebb48a7c0981ecb6d4afcbbb25ffcea0..b313f213822f0fd5ba6448f6f6f453cfda4c7e23
> 100644
> --- a/drivers/xen/efi.c
> +++ b/drivers/xen/efi.c
> @@ -26,6 +26,7 @@
>
> #include <xen/interface/xen.h>
> #include <xen/interface/platform.h>
> +#include <xen/page.h>
> #include <xen/xen.h>
> #include <xen/xen-ops.h>
>
> @@ -40,6 +41,37 @@
>
> #define efi_data(op) (op.u.efi_runtime_call)
>
> +static_assert(XEN_PAGE_SHIFT == EFI_PAGE_SHIFT,
> + "Mismatch between EFI_PAGE_SHIFT and XEN_PAGE_SHIFT");
> +
> +bool xen_efi_mem_info_query(u64 phys_addr, struct xen_efi_mem_info *md)
> +{
> + struct xen_platform_op op = {
> + .cmd = XENPF_firmware_info,
> + .u.firmware_info = {
> + .type = XEN_FW_EFI_INFO,
> + .index = XEN_FW_EFI_MEM_INFO,
> + .u.efi_info.mem.addr = phys_addr,
> + .u.efi_info.mem.size = ((u64)-1ULL) - phys_addr,
> + }
> + };
> + union xenpf_efi_info *info = &op.u.firmware_info.u.efi_info;
> + int rc;
> +
> + memset(md, 0, sizeof(*md)); /* initialize md even on failure */
> + rc = HYPERVISOR_platform_op(&op);
> + if (rc) {
> + pr_warn("Could not obtain information on address %llu from
> Xen: "
> + "error %d\n", phys_addr, rc);
> + return false;
> + }
> + md->addr = info->mem.addr;
> + md->size = info->mem.size;
> + md->attr = info->mem.attr;
> + md->type = info->mem.type;
> + return true;
> +}
> +
> static efi_status_t xen_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
> {
> struct xen_platform_op op = INIT_EFI_OP(get_time);
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index
> d2b84c2fec39f0268324d1a38a73ed67786973c9..0598869cdc924aef0e2b9cacc4450b728e1a98c7
> 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -1327,1 +1327,19 @@ struct linux_efi_coco_secret_area {
> +/* Result of a XEN_FW_EFI_MEM_INFO query */
> +struct xen_efi_mem_info {
> + uint64_t addr; /* address queried */
> + uint64_t size; /* remaining bytes in memory region */
> + uint64_t attr; /* attributes */
> + uint32_t type; /* type */
> +};
> +
> +#if IS_ENABLED(CONFIG_XEN_EFI)
> +extern bool xen_efi_mem_info_query(u64 phys_addr, struct xen_efi_mem_info
> *out_md);
> +#else
> +static inline bool xen_efi_mem_info_query(u64 phys_addr, struct
> xen_efi_mem_info *out_md)
> +{
> + BUILD_BUG();
> + return false;
> +}
> +#endif
> +
> #endif /* _LINUX_EFI_H */
> --
> Sincerely,
> Demi Marie Obenour (she/her/hers)
> Invisible Things Lab
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