linux-kernel - [PATCH v3 5/5] efi: Warn if trying to reserve memory under Xen

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Date:   Thu, 19 Jan 2023 14:04:00 -0500
From:   Demi Marie Obenour <demi@...isiblethingslab.com>
To:     Ard Biesheuvel <ardb@...nel.org>, Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
Cc:     Demi Marie Obenour <demi@...isiblethingslab.com>,
        Marek Marczykowski-Górecki 
        <marmarek@...isiblethingslab.com>, linux-efi@...r.kernel.org,
        linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org
Subject: [PATCH v3 5/5] efi: Warn if trying to reserve memory under Xen

Doing so cannot work and should never happen.

Signed-off-by: Demi Marie Obenour <demi@...isiblethingslab.com>
Tested-by: Marek Marczykowski-Górecki <marmarek@...isiblethingslab.com>
---
 drivers/firmware/efi/efi.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index b49fcde06ca0ff5347047666f38b9309bd9cfe26..902f323499d8acc4f2b846a78993eb201448acad 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -519,6 +519,10 @@ void __init __weak efi_arch_mem_reserve(phys_addr_t addr, u64 size) {}
  */
 void __init efi_mem_reserve(phys_addr_t addr, u64 size)
 {
+	/* efi_mem_reserve() does not work under Xen */
+	if (WARN_ON_ONCE(efi_enabled(EFI_PARAVIRT)))
+		return;
+
 	if (!memblock_is_region_reserved(addr, size))
 		memblock_reserve(addr, size);
 
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab